Add custom patch command "Move patch into new commit before the original commit"

This is often useful to extract preparatory refactoring commits from a bigger
one.

pkg/gui/controllers/custom_patch_options_menu_action.go

@@ -64,6 +64,12 @@ func (self *CustomPatchOptionsMenuAction) Call() error {
 				OnPress: self.handlePullPatchIntoNewCommit,
 				Key:     'n',
 			},
+			{
+				Label:   self.c.Tr.MovePatchIntoNewCommitBefore,
+				Tooltip: self.c.Tr.MovePatchIntoNewCommitBeforeTooltip,
+				OnPress: self.handlePullPatchIntoNewCommitBefore,
+				Key:     'N',
+			},
 		}...)
 
 		if self.c.Context().Current().GetKey() == self.c.Contexts().LocalCommits.GetKey() {
@@ -223,6 +229,41 @@ func (self *CustomPatchOptionsMenuAction) handlePullPatchIntoNewCommit() error {
 	return nil
 }
 
+func (self *CustomPatchOptionsMenuAction) handlePullPatchIntoNewCommitBefore() error {
+	if ok, err := self.validateNormalWorkingTreeState(); !ok {
+		return err
+	}
+
+	self.returnFocusFromPatchExplorerIfNecessary()
+
+	commitIndex := self.getPatchCommitIndex()
+	self.c.Helpers().Commits.OpenCommitMessagePanel(
+		&helpers.OpenCommitMessagePanelOpts{
+			// Pass a commit index of one less than the moved-from commit, so that
+			// you can press up arrow once to recall the original commit message:
+			CommitIndex:      commitIndex - 1,
+			InitialMessage:   "",
+			SummaryTitle:     self.c.Tr.CommitSummaryTitle,
+			DescriptionTitle: self.c.Tr.CommitDescriptionTitle,
+			PreserveMessage:  false,
+			OnConfirm: func(summary string, description string) error {
+				return self.c.WithWaitingStatus(self.c.Tr.RebasingStatus, func(gocui.Task) error {
+					self.c.Helpers().Commits.CloseCommitMessagePanel()
+					self.c.LogAction(self.c.Tr.Actions.MovePatchIntoNewCommit)
+					err := self.c.Git().Patch.PullPatchIntoNewCommitBefore(self.c.Model().Commits, commitIndex, summary, description)
+					if err := self.c.Helpers().MergeAndRebase.CheckMergeOrRebase(err); err != nil {
+						return err
+					}
+					self.c.Context().Push(self.c.Contexts().LocalCommits, types.OnFocusOpts{})
+					return nil
+				})
+			},
+		},
+	)
+
+	return nil
+}
+
 func (self *CustomPatchOptionsMenuAction) handleApplyPatch(reverse bool) error {
 	self.returnFocusFromPatchExplorerIfNecessary()