Mitigate execext.Expand problems on Windows

Closes #170

Co-authored-by: mikynov <micnov@gmail.com>

CHANGELOG.md

@@ -11,7 +11,9 @@
   Mode is enabled
   ([#166](https://github.com/go-task/task/issues/166));
 - Fix file timestamp issue when the file name has spaces
-  ([#176](https://github.com/go-task/task/issues/176)).
+  ([#176](https://github.com/go-task/task/issues/176));
+- Mitigating path expanding issues on Windows
+  ([#170](https://github.com/go-task/task/pull/170)).
 
 ## v2.3.0 - 2019-01-02
 

internal/execext/exec.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"mvdan.cc/sh/expand"
@@ -72,6 +73,7 @@ func IsExitError(err error) bool {
 // Expand is a helper to mvdan.cc/shell.Fields that returns the first field
 // if available.
 func Expand(s string) (string, error) {
+	s = filepath.ToSlash(s)
 	s = strings.Replace(s, " ", `\ `, -1)
 	fields, err := shell.Fields(s, nil)
 	if err != nil {