Show update-ref commands in rebase todo list

This is useful when working with stacked branches, because you can now move
"pick" entries across an update-ref command and you can tell exactly which
branch the commit will end up in.

It's also useful to spot situations where the --update-refs option didn't work
as desired. For example, if you duplicate a branch and want to rebase only one
of the branches but not the other (maybe for testing); if you have
rebase.updateRefs=true in your git config, then rebasing one branch will move
the other branch along. To solve this we'll have to introduce a way to delete
the update-ref entry (maybe by hitting backspace?); this is out of scope for
this PR, so for now users will have to type "git rebase --edit-todo" into the
custom command prompt to sort this out.

We will also have to prevent users from trying to turn update-ref commands into
other commands like "pick" or "drop"; we'll do this later in this branch.

pkg/commands/git_commands/commit_loader.go

@@ -311,7 +311,9 @@ func (self *CommitLoader) getInteractiveRebasingCommits() ([]*models.Commit, err
 	}
 
 	for _, t := range todos {
-		if t.Commit == "" {
+		if t.Command == todo.UpdateRef {
+			t.Msg = strings.TrimPrefix(t.Ref, "refs/heads/")
+		} else if t.Commit == "" {
 			// Command does not have a commit associated, skip
 			continue
 		}

pkg/gui/commits_panel.go

@@ -1,6 +1,7 @@
 package gui
 
 import (
+	"github.com/fsmiamoto/git-todo-parser/todo"
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
 	"github.com/jesseduffield/lazygit/pkg/utils"
@@ -34,6 +35,13 @@ func (gui *Gui) branchCommitsRenderToMain() error {
 	commit := gui.State.Contexts.LocalCommits.GetSelected()
 	if commit == nil {
 		task = types.NewRenderStringTask(gui.c.Tr.NoCommitsThisBranch)
+	} else if commit.Action == todo.UpdateRef {
+		task = types.NewRenderStringTask(
+			utils.ResolvePlaceholderString(
+				gui.c.Tr.UpdateRefHere,
+				map[string]string{
+					"ref": commit.Name,
+				}))
 	} else {
 		cmdObj := gui.git.Commit.ShowCmdObj(commit.Sha, gui.State.Modes.Filtering.GetPath(),
 			gui.IgnoreWhitespaceInDiffView)

pkg/gui/presentation/commits.go

@@ -347,7 +347,7 @@ func getShaColor(
 		return getBisectStatusColor(bisectStatus)
 	}
 
-	diffed := commit.Sha == diffName
+	diffed := commit.Sha != "" && commit.Sha == diffName
 	shaColor := theme.DefaultTextColor
 	switch commit.Status {
 	case models.StatusUnpushed:

pkg/i18n/english.go

@@ -105,6 +105,7 @@ type TranslationSet struct {
 	SureResetCommitAuthor               string
 	LcRenameCommitEditor                string
 	NoCommitsThisBranch                 string
+	UpdateRefHere                       string
 	Error                               string
 	LcSelectHunk                        string
 	LcNavigateConflicts                 string
@@ -754,6 +755,7 @@ func EnglishTranslationSet() TranslationSet {
 		LcSquashDown:                        "squash down",
 		LcFixupCommit:                       "fixup commit",
 		NoCommitsThisBranch:                 "No commits for this branch",
+		UpdateRefHere:                       "Update branch '{{.ref}}' here",
 		CannotSquashOrFixupFirstCommit:      "There's no commit below to squash into",
 		Fixup:                               "Fixup",
 		SureFixupThisCommit:                 "Are you sure you want to 'fixup' this commit? It will be merged into the commit below",