rebase --abort: do not update branch ref

If a non-interactive rebase of a ref fails at commit X and is aborted by
the user, the ref will be updated twice. First to point at X (with the
reflog message "rebase finished: $head_name onto $onto"), and then back
to $orig_head. It should not be updated at all.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase.sh

@@ -274,15 +274,16 @@ do
 			die "No rebase in progress?"
 
 		git rerere clear
-		if test -d "$dotest"
-		then
-			GIT_QUIET=$(cat "$dotest/quiet")
-			move_to_original_branch
-		else
-			dotest="$GIT_DIR"/rebase-apply
-			GIT_QUIET=$(cat "$dotest/quiet")
-			move_to_original_branch
-		fi
+
+		test -d "$dotest" || dotest="$GIT_DIR"/rebase-apply
+
+		head_name="$(cat "$dotest"/head-name)" &&
+		case "$head_name" in
+		refs/*)
+			git symbolic-ref HEAD $head_name ||
+			die "Could not move back to $head_name"
+			;;
+		esac
 		git reset --hard $(cat "$dotest/orig-head")
 		rm -r "$dotest"
 		exit

t/t3407-rebase-abort.sh

@@ -72,6 +72,18 @@ testrebase() {
 		test $(git rev-parse to-rebase) = $(git rev-parse pre-rebase) &&
 		test ! -d "$dotest"
 	'
+
+	test_expect_success "rebase$type --abort does not update reflog" '
+		cd "$work_dir" &&
+		# Clean up the state from the previous one
+		git reset --hard pre-rebase &&
+		git reflog show to-rebase > reflog_before &&
+		test_must_fail git rebase$type master &&
+		git rebase --abort &&
+		git reflog show to-rebase > reflog_after &&
+		test_cmp reflog_before reflog_after &&
+		rm reflog_before reflog_after
+	'
 }
 
 testrebase "" .git/rebase-apply