diff --git a/vendor/modules.txt b/vendor/modules.txt
index 128c3fc0..faebaa02 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -37,7 +37,7 @@ golang.org/x/xerrors
 golang.org/x/xerrors/internal
 # gopkg.in/yaml.v2 v2.2.2
 gopkg.in/yaml.v2
-# mvdan.cc/sh/v3 v3.0.0-beta1
+# mvdan.cc/sh/v3 v3.0.2
 mvdan.cc/sh/v3/expand
 mvdan.cc/sh/v3/interp
 mvdan.cc/sh/v3/pattern
diff --git a/vendor/mvdan.cc/sh/v3/expand/braces.go b/vendor/mvdan.cc/sh/v3/expand/braces.go
index 482f8116..9914fe44 100644
--- a/vendor/mvdan.cc/sh/v3/expand/braces.go
+++ b/vendor/mvdan.cc/sh/v3/expand/braces.go
@@ -24,13 +24,13 @@ func Braces(word *syntax.Word) []*syntax.Word {
 			continue
 		}
 		if br.Sequence {
-			var from, to int
-			if br.Chars {
+			chars := false
+			from, err1 := strconv.Atoi(br.Elems[0].Lit())
+			to, err2 := strconv.Atoi(br.Elems[1].Lit())
+			if err1 != nil || err2 != nil {
+				chars = true
 				from = int(br.Elems[0].Lit()[0])
 				to = int(br.Elems[1].Lit()[0])
-			} else {
-				from, _ = strconv.Atoi(br.Elems[0].Lit())
-				to, _ = strconv.Atoi(br.Elems[1].Lit())
 			}
 			upward := from <= to
 			incr := 1
@@ -54,7 +54,7 @@ func Braces(word *syntax.Word) []*syntax.Word {
 				next := *word
 				next.Parts = next.Parts[i+1:]
 				lit := &syntax.Lit{}
-				if br.Chars {
+				if chars {
 					lit.Value = string(n)
 				} else {
 					lit.Value = strconv.Itoa(n)
diff --git a/vendor/mvdan.cc/sh/v3/expand/expand.go b/vendor/mvdan.cc/sh/v3/expand/expand.go
index 0186a8fc..847cd46d 100644
--- a/vendor/mvdan.cc/sh/v3/expand/expand.go
+++ b/vendor/mvdan.cc/sh/v3/expand/expand.go
@@ -159,6 +159,8 @@ func Document(cfg *Config, word *syntax.Word) (string, error) {
 	return cfg.fieldJoin(field), nil
 }
 
+const patMode = pattern.Filenames | pattern.Braces
+
 // Pattern expands a single shell word as a pattern, using syntax.QuotePattern
 // on any non-quoted parts of the input word. The result can be used on
 // syntax.TranslatePattern directly.
@@ -174,7 +176,7 @@ func Pattern(cfg *Config, word *syntax.Word) (string, error) {
 	buf := cfg.strBuilder()
 	for _, part := range field {
 		if part.quote > quoteNone {
-			buf.WriteString(pattern.QuoteMeta(part.val))
+			buf.WriteString(pattern.QuoteMeta(part.val, patMode))
 		} else {
 			buf.WriteString(part.val)
 		}
@@ -345,11 +347,11 @@ func (cfg *Config) escapedGlobField(parts []fieldPart) (escaped string, glob boo
 	buf := cfg.strBuilder()
 	for _, part := range parts {
 		if part.quote > quoteNone {
-			buf.WriteString(pattern.QuoteMeta(part.val))
+			buf.WriteString(pattern.QuoteMeta(part.val, patMode))
 			continue
 		}
 		buf.WriteString(part.val)
-		if pattern.HasMeta(part.val) {
+		if pattern.HasMeta(part.val, patMode) {
 			glob = true
 		}
 	}
@@ -367,9 +369,10 @@ func Fields(cfg *Config, words ...*syntax.Word) ([]string, error) {
 	fields := make([]string, 0, len(words))
 	dir := cfg.envGet("PWD")
 	for _, word := range words {
-		afterBraces := []*syntax.Word{word}
-		if syntax.SplitBraces(word) {
-			afterBraces = Braces(word)
+		word := *word // make a copy, since SplitBraces replaces the Parts slice
+		afterBraces := []*syntax.Word{&word}
+		if syntax.SplitBraces(&word) {
+			afterBraces = Braces(&word)
 		}
 		for _, word2 := range afterBraces {
 			wfields, err := cfg.wordFields(word2.Parts)
@@ -540,7 +543,6 @@ func (cfg *Config) wordFields(wps []syntax.WordPart) ([][]fieldPart, error) {
 			}
 			curField = append(curField, fp)
 		case *syntax.DblQuoted:
-			allowEmpty = true
 			if len(x.Parts) == 1 {
 				pe, _ := x.Parts[0].(*syntax.ParamExp)
 				if elems := cfg.quotedElems(pe); elems != nil {
@@ -556,6 +558,7 @@ func (cfg *Config) wordFields(wps []syntax.WordPart) ([][]fieldPart, error) {
 					continue
 				}
 			}
+			allowEmpty = true
 			wfield, err := cfg.wordField(x.Parts, quoteDouble)
 			if err != nil {
 				return nil, err
diff --git a/vendor/mvdan.cc/sh/v3/interp/interp.go b/vendor/mvdan.cc/sh/v3/interp/interp.go
index 257ed04f..c3e8e347 100644
--- a/vendor/mvdan.cc/sh/v3/interp/interp.go
+++ b/vendor/mvdan.cc/sh/v3/interp/interp.go
@@ -745,7 +745,6 @@ func (r *Runner) sub() *Runner {
 		Env:         r.Env,
 		Dir:         r.Dir,
 		Params:      r.Params,
-		Funcs:       r.Funcs,
 		execHandler: r.execHandler,
 		openHandler: r.openHandler,
 		stdin:       r.stdin,
@@ -766,6 +765,10 @@ func (r *Runner) sub() *Runner {
 	for k, v := range r.cmdVars {
 		r2.cmdVars[k] = v
 	}
+	r2.Funcs = make(map[string]*syntax.Stmt, len(r.Funcs))
+	for k, v := range r.Funcs {
+		r2.Funcs[k] = v
+	}
 	r2.dirStack = append(r2.dirBootstrap[:0], r.dirStack...)
 	r2.fillExpandConfig(r.ectx)
 	r2.didReset = true
diff --git a/vendor/mvdan.cc/sh/v3/pattern/pattern.go b/vendor/mvdan.cc/sh/v3/pattern/pattern.go
index 185f2d80..a36e30c4 100644
--- a/vendor/mvdan.cc/sh/v3/pattern/pattern.go
+++ b/vendor/mvdan.cc/sh/v3/pattern/pattern.go
@@ -16,8 +16,8 @@ import (
 	"strings"
 )
 
-// TODO: support Mode in the other APIs too
-
+// Mode can be used to supply a number of options to the package's functions.
+// Not all functions change their behavior with all of the options below.
 type Mode uint
 
 const (
@@ -254,13 +254,17 @@ func charClass(s string) (string, error) {
 // This can be useful to avoid extra work, like TranslatePattern. Note that this
 // function cannot be used to avoid QuotePattern, as backslashes are quoted by
 // that function but ignored here.
-func HasMeta(pat string) bool {
+func HasMeta(pat string, mode Mode) bool {
 	for i := 0; i < len(pat); i++ {
 		switch pat[i] {
 		case '\\':
 			i++
 		case '*', '?', '[':
 			return true
+		case '{':
+			if mode&Braces != 0 {
+				return true
+			}
 		}
 	}
 	return false
@@ -270,11 +274,16 @@ func HasMeta(pat string) bool {
 // given text. The returned string is a pattern that matches the literal text.
 //
 // For example, QuoteMeta(`foo*bar?`) returns `foo\*bar\?`.
-func QuoteMeta(pat string) string {
+func QuoteMeta(pat string, mode Mode) string {
 	any := false
 loop:
 	for _, r := range pat {
 		switch r {
+		case '{':
+			if mode&Braces == 0 {
+				continue
+			}
+			fallthrough
 		case '*', '?', '[', '\\':
 			any = true
 			break loop
@@ -288,6 +297,10 @@ loop:
 		switch r {
 		case '*', '?', '[', '\\':
 			buf.WriteByte('\\')
+		case '{':
+			if mode&Braces != 0 {
+				buf.WriteByte('\\')
+			}
 		}
 		buf.WriteRune(r)
 	}
diff --git a/vendor/mvdan.cc/sh/v3/shell/source.go b/vendor/mvdan.cc/sh/v3/shell/source.go
deleted file mode 100644
index 13261ffd..00000000
--- a/vendor/mvdan.cc/sh/v3/shell/source.go
+++ /dev/null
@@ -1,57 +0,0 @@
-// Copyright (c) 2018, Daniel Martí <mvdan@mvdan.cc>
-// See LICENSE for licensing information
-
-package shell
-
-import (
-	"context"
-	"fmt"
-	"os"
-
-	"mvdan.cc/sh/v3/expand"
-	"mvdan.cc/sh/v3/interp"
-	"mvdan.cc/sh/v3/syntax"
-)
-
-// SourceFile sources a shell file from disk and returns the variables
-// declared in it. It is a convenience function that uses a default shell
-// parser, parses a file from disk, and calls SourceNode.
-//
-// This function should be used with caution, as it can interpret arbitrary
-// code. Untrusted shell programs shoudn't be sourced outside of a sandbox
-// environment.
-func SourceFile(ctx context.Context, path string) (map[string]expand.Variable, error) {
-	f, err := os.Open(path)
-	if err != nil {
-		return nil, fmt.Errorf("could not open: %v", err)
-	}
-	defer f.Close()
-	file, err := syntax.NewParser().Parse(f, path)
-	if err != nil {
-		return nil, fmt.Errorf("could not parse: %v", err)
-	}
-	return SourceNode(ctx, file)
-}
-
-// SourceNode sources a shell program from a node and returns the
-// variables declared in it. It accepts the same set of node types that
-// interp/Runner.Run does.
-//
-// This function should be used with caution, as it can interpret arbitrary
-// code. Untrusted shell programs shoudn't be sourced outside of a sandbox
-// environment.
-func SourceNode(ctx context.Context, node syntax.Node) (map[string]expand.Variable, error) {
-	r, _ := interp.New()
-	if err := r.Run(ctx, node); err != nil {
-		return nil, fmt.Errorf("could not run: %v", err)
-	}
-	// delete the internal shell vars that the user is not
-	// interested in
-	delete(r.Vars, "PWD")
-	delete(r.Vars, "UID")
-	delete(r.Vars, "HOME")
-	delete(r.Vars, "PATH")
-	delete(r.Vars, "IFS")
-	delete(r.Vars, "OPTIND")
-	return r.Vars, nil
-}
diff --git a/vendor/mvdan.cc/sh/v3/syntax/braces.go b/vendor/mvdan.cc/sh/v3/syntax/braces.go
index 0baa43a0..dca854fd 100644
--- a/vendor/mvdan.cc/sh/v3/syntax/braces.go
+++ b/vendor/mvdan.cc/sh/v3/syntax/braces.go
@@ -129,7 +129,6 @@ func SplitBraces(word *Word) bool {
 					broken = true
 				}
 				if !broken {
-					br.Chars = chars[0]
 					acc.Parts = append(acc.Parts, br)
 					break
 				}
diff --git a/vendor/mvdan.cc/sh/v3/syntax/lexer.go b/vendor/mvdan.cc/sh/v3/syntax/lexer.go
index ac144cc2..b3daba6d 100644
--- a/vendor/mvdan.cc/sh/v3/syntax/lexer.go
+++ b/vendor/mvdan.cc/sh/v3/syntax/lexer.go
@@ -256,6 +256,7 @@ skipSpace:
 			for r != '\n' && r != utf8.RuneSelf {
 				if r == escNewl {
 					p.litBs = append(p.litBs, '\\', '\n')
+					break
 				}
 				r = p.rune()
 			}
@@ -316,6 +317,7 @@ skipSpace:
 			} else {
 				p.tok = rightParen
 				p.quote = noState
+				p.rune() // we are tokenizing manually
 			}
 		default: // including '(', '|'
 			p.advanceLitRe(r)
diff --git a/vendor/mvdan.cc/sh/v3/syntax/nodes.go b/vendor/mvdan.cc/sh/v3/syntax/nodes.go
index e3d08b24..b8fa71bf 100644
--- a/vendor/mvdan.cc/sh/v3/syntax/nodes.go
+++ b/vendor/mvdan.cc/sh/v3/syntax/nodes.go
@@ -409,9 +409,9 @@ type Word struct {
 func (w *Word) Pos() Pos { return w.Parts[0].Pos() }
 func (w *Word) End() Pos { return w.Parts[len(w.Parts)-1].End() }
 
-// Lit returns the word as a literal value, if the word consists of *syntax.Lit
-// nodes only. An empty string is returned otherwise. Words with multiple
-// literals, which can appear in some edge cases, are handled properly.
+// Lit returns the word as a literal value, if the word consists of *Lit nodes
+// only. An empty string is returned otherwise. Words with multiple literals,
+// which can appear in some edge cases, are handled properly.
 //
 // For example, the word "foo" will return "foo", but the word "foo${bar}" will
 // return "".
@@ -859,12 +859,11 @@ type LetClause struct {
 func (l *LetClause) Pos() Pos { return l.Let }
 func (l *LetClause) End() Pos { return l.Exprs[len(l.Exprs)-1].End() }
 
-// BraceExp represents a Bash brace expression, such as "{x,y}" or "{1..10}".
+// BraceExp represents a Bash brace expression, such as "{a,f}" or "{1..10}".
 //
 // This node will only appear as a result of SplitBraces.
 type BraceExp struct {
 	Sequence bool // {x..y[..incr]} instead of {x,y[,...]}
-	Chars    bool // sequence is of chars, not numbers (TODO: remove)
 	Elems    []*Word
 }
 
diff --git a/vendor/mvdan.cc/sh/v3/syntax/parser.go b/vendor/mvdan.cc/sh/v3/syntax/parser.go
index bce05999..e445b0ad 100644
--- a/vendor/mvdan.cc/sh/v3/syntax/parser.go
+++ b/vendor/mvdan.cc/sh/v3/syntax/parser.go
@@ -14,7 +14,7 @@ import (
 
 // ParserOption is a function which can be passed to NewParser
 // to alter its behaviour. To apply option to existing Parser
-// call it directly, for example syntax.KeepComments(true)(parser).
+// call it directly, for example KeepComments(true)(parser).
 type ParserOption func(*Parser)
 
 // KeepComments makes the parser parse comments and attach them to
@@ -524,9 +524,13 @@ func (p *Parser) unquotedWordPart(buf *bytes.Buffer, wp WordPart, quotes bool) (
 }
 
 func (p *Parser) doHeredocs() {
+	hdocs := p.heredocs[p.buriedHdocs:]
+	if len(hdocs) == 0 {
+		// Nothing do do; don't even issue a read.
+		return
+	}
 	p.rune() // consume '\n', since we know p.tok == _Newl
 	old := p.quote
-	hdocs := p.heredocs[p.buriedHdocs:]
 	p.heredocs = p.heredocs[:p.buriedHdocs]
 	for i, r := range hdocs {
 		if p.err != nil {
@@ -840,7 +844,7 @@ func (p *Parser) invalidStmtStart() {
 }
 
 func (p *Parser) getWord() *Word {
-	if parts := p.wordParts(); len(parts) > 0 {
+	if parts := p.wordParts(); len(parts) > 0 && p.err == nil {
 		return p.word(parts)
 	}
 	return nil
@@ -1546,13 +1550,15 @@ func (p *Parser) hasValidIdent() bool {
 	}
 	if end := p.eqlOffs; end > 0 {
 		if p.val[end-1] == '+' && p.lang != LangPOSIX {
-			end--
+			end-- // a+=x
 		}
 		if ValidName(p.val[:end]) {
 			return true
 		}
+	} else if !ValidName(p.val) {
+		return false // *[i]=x
 	}
-	return p.r == '['
+	return p.r == '[' // a[i]=x
 }
 
 func (p *Parser) getAssign(needEqual bool) *Assign {
diff --git a/vendor/mvdan.cc/sh/v3/syntax/printer.go b/vendor/mvdan.cc/sh/v3/syntax/printer.go
index 2bb80e47..8ab1bdcd 100644
--- a/vendor/mvdan.cc/sh/v3/syntax/printer.go
+++ b/vendor/mvdan.cc/sh/v3/syntax/printer.go
@@ -15,7 +15,7 @@ import (
 
 // PrinterOption is a function which can be passed to NewPrinter
 // to alter its behaviour. To apply option to existing Printer
-// call it directly, for example syntax.KeepPadding(true)(printer).
+// call it directly, for example KeepPadding(true)(printer).
 type PrinterOption func(*Printer)
 
 // Indent sets the number of spaces used for indentation. If set to 0,
@@ -414,13 +414,13 @@ func (p *Printer) flushHeredocs() {
 					bufWriter: &extra,
 					line:      r.Hdoc.Pos().Line(),
 				}
-				p.tabsPrinter.word(r.Hdoc)
+				p.tabsPrinter.wordParts(r.Hdoc.Parts, true)
 				p.indent()
 			} else {
 				p.indent()
 			}
 		} else if r.Hdoc != nil {
-			p.word(r.Hdoc)
+			p.wordParts(r.Hdoc.Parts, true)
 		}
 		p.unquotedWord(r.Word)
 		if r.Hdoc != nil {
@@ -478,6 +478,11 @@ func (p *Printer) semiRsrv(s string, pos Pos) {
 
 func (p *Printer) flushComments() {
 	for i, c := range p.pendingComments {
+		if i == 0 {
+			// Flush any pending heredocs first. Otherwise, the
+			// comments would become part of a heredoc body.
+			p.flushHeredocs()
+		}
 		p.firstLine = false
 		// We can't call any of the newline methods, as they call this
 		// function and we'd recurse forever.