rebase --merge: fix reflog when continuing

The reflog message for a conflict resolution committed by "rebase
--continue" looks like

	rebase (continue): commit subject line

Unfortunately the reflog message each subsequent pick look like

	rebase (continue) (pick): commit subject line

Fix this by setting the reflog message for "rebase --continue" in
sequencer_continue() so it does not affect subsequent commits. This
introduces a memory leak similar to the one leaking GIT_REFLOG_ACTION
in pick_commits(). Both of these will be fixed in a future series that
stops the sequencer calling setenv().

If we fail to commit the staged changes then we error out so
GIT_REFLOG_ACTION does not need to be reset in that case.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rebase.c

@@ -1271,8 +1271,6 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		int fd;
 
 		options.action = "continue";
-		set_reflog_action(&options);
-
 		/* Sanity check */
 		if (get_oid("HEAD", &head))
 			die(_("Cannot read HEAD"));

sequencer.c

@@ -4785,6 +4785,8 @@ int sequencer_continue(struct repository *r, struct replay_opts *opts)
 	if (read_populate_opts(opts))
 		return -1;
 	if (is_rebase_i(opts)) {
+		char *previous_reflog_action;
+
 		if ((res = read_populate_todo(r, &todo_list, opts)))
 			goto release_todo_list;
 
@@ -4795,10 +4797,13 @@ int sequencer_continue(struct repository *r, struct replay_opts *opts)
 			unlink(rebase_path_dropped());
 		}
 
+		previous_reflog_action = xstrdup(getenv(GIT_REFLOG_ACTION));
+		setenv(GIT_REFLOG_ACTION, reflog_message(opts, "continue", NULL), 1);
 		if (commit_staged_changes(r, opts, &todo_list)) {
 			res = -1;
 			goto release_todo_list;
 		}
+		setenv(GIT_REFLOG_ACTION, previous_reflog_action, 1);
 	} else if (!file_exists(get_todo_path(opts)))
 		return continue_single_pick(r, opts);
 	else if ((res = read_populate_todo(r, &todo_list, opts)))

t/t3406-rebase-message.sh

@@ -17,6 +17,7 @@ test_expect_success 'setup' '
 
 	git checkout -b conflicts O &&
 	test_commit P &&
+	test_commit conflict-X fileX &&
 	test_commit Q &&
 
 	git checkout -b topic O &&
@@ -107,13 +108,17 @@ test_reflog () {
 			GIT_REFLOG_ACTION="$reflog_action" &&
 			export GIT_REFLOG_ACTION
 		fi &&
-		git rebase $mode main
+		test_must_fail git rebase $mode main &&
+		echo resolved >fileX &&
+		git add fileX &&
+		git rebase --continue
 	) &&
 
-	git log -g --format=%gs -4 >actual &&
+	git log -g --format=%gs -5 >actual &&
 	write_reflog_expect <<-EOF &&
 	${reflog_action:-rebase} (finish): returning to refs/heads/conflicts
 	${reflog_action:-rebase} (pick): Q
+	${reflog_action:-rebase} (continue): conflict-X
 	${reflog_action:-rebase} (pick): P
 	${reflog_action:-rebase} (start): checkout main
 	EOF