Disable moving merge commits

Not much of a change in behavior, because moving merge commits was already not
possible. However, it failed with a cryptic error message ("Todo fa1afe1 not
found in git-rebase-todo"), so disable it properly instead.

pkg/gui/controllers/local_commits_controller.go

@@ -1420,6 +1420,10 @@ func (self *LocalCommitsController) midRebaseCommandEnabled(selectedCommits []*m
 // Ensures that if we are mid-rebase, we're only selecting commits that can be moved
 func (self *LocalCommitsController) midRebaseMoveCommandEnabled(selectedCommits []*models.Commit, startIdx int, endIdx int) *types.DisabledReason {
 	if !self.isRebasing() {
+		if lo.SomeBy(selectedCommits, func(c *models.Commit) bool { return c.IsMerge() }) {
+			return &types.DisabledReason{Text: self.c.Tr.CannotMoveMergeCommit}
+		}
+
 		return nil
 	}
 

pkg/i18n/english.go

@@ -160,6 +160,7 @@ type TranslationSet struct {
 	MoveDownCommit                        string
 	MoveUpCommit                          string
 	CannotMoveAnyFurther                  string
+	CannotMoveMergeCommit                 string
 	EditCommit                            string
 	EditCommitTooltip                     string
 	AmendCommitTooltip                    string
@@ -1153,6 +1154,7 @@ func EnglishTranslationSet() *TranslationSet {
 		MoveDownCommit:                       "Move commit down one",
 		MoveUpCommit:                         "Move commit up one",
 		CannotMoveAnyFurther:                 "Cannot move any further",
+		CannotMoveMergeCommit:                "Cannot move a merge commit",
 		EditCommit:                           "Edit (start interactive rebase)",
 		EditCommitTooltip:                    "Edit the selected commit. Use this to start an interactive rebase from the selected commit. When already mid-rebase, this will mark the selected commit for editing, which means that upon continuing the rebase, the rebase will pause at the selected commit to allow you to make changes.",
 		AmendCommitTooltip:                   "Amend commit with staged changes. If the selected commit is the HEAD commit, this will perform `git commit --amend`. Otherwise the commit will be amended via a rebase.",