Give better visual feedback when checking out the previous branch

pkg/commands/git_commands/branch.go

@@ -116,6 +116,22 @@ func (self *BranchCommands) CurrentBranchName() (string, error) {
 	return strings.TrimSpace(output), nil
 }
 
+// Gets the full ref name of the previously checked out branch. Can return an empty string (but no
+// error) e.g. when the previously checked out thing was a detached head.
+func (self *BranchCommands) PreviousRef() (string, error) {
+	cmdArgs := NewGitCmd("rev-parse").
+		Arg("--symbolic-full-name").
+		Arg("@{-1}").
+		ToArgv()
+
+	output, err := self.cmd.New(cmdArgs).DontLog().RunWithOutput()
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(output), nil
+}
+
 // LocalDelete delete branch locally
 func (self *BranchCommands) LocalDelete(branches []string, force bool) error {
 	cmdArgs := NewGitCmd("branch").

pkg/gui/controllers/branches_controller.go

@@ -490,7 +490,7 @@ func (self *BranchesController) forceCheckout() error {
 
 func (self *BranchesController) checkoutPreviousBranch() error {
 	self.c.LogAction(self.c.Tr.Actions.CheckoutBranch)
-	return self.c.Helpers().Refs.CheckoutRef("-", types.CheckoutRefOptions{})
+	return self.c.Helpers().Refs.CheckoutPreviousRef()
 }
 
 func (self *BranchesController) checkoutByName() error {

pkg/gui/controllers/helpers/refs_helper.go

@@ -163,6 +163,15 @@ func (self *RefsHelper) CheckoutRemoteBranch(fullBranchName string, localBranchN
 	})
 }
 
+func (self *RefsHelper) CheckoutPreviousRef() error {
+	previousRef, err := self.c.Git().Branch.PreviousRef()
+	if err == nil && strings.HasPrefix(previousRef, "refs/heads/") {
+		return self.CheckoutRef(strings.TrimPrefix(previousRef, "refs/heads/"), types.CheckoutRefOptions{})
+	}
+
+	return self.CheckoutRef("-", types.CheckoutRefOptions{})
+}
+
 func (self *RefsHelper) GetCheckedOutRef() *models.Branch {
 	if len(self.c.Model().Branches) == 0 {
 		return nil