pull: allow dirty tree when rebase.autostash enabled

rebase learned to stash changes when it encounters a dirty work tree,
but git pull --rebase does not.

Only verify if the working tree is dirty when rebase.autostash is not
enabled.

Signed-off-by: Kevin Daudt <me@ikke.info>
Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pull.c

@@ -823,10 +823,14 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		hashclr(orig_head);
 
 	if (opt_rebase) {
+		int autostash = 0;
+
 		if (is_null_sha1(orig_head) && !is_cache_unborn())
 			die(_("Updating an unborn branch with changes added to the index."));
 
-		die_on_unclean_work_tree(prefix);
+		git_config_get_bool("rebase.autostash", &autostash);
+		if (!autostash)
+			die_on_unclean_work_tree(prefix);
 
 		if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 			hashclr(rebase_fork_point);

t/t5520-pull.sh

@@ -122,6 +122,18 @@ test_expect_success '--rebase' '
 	test $(git rev-parse HEAD^) = $(git rev-parse copy) &&
 	test new = $(git show HEAD:file2)
 '
+
+test_expect_success 'pull --rebase succeeds with dirty working directory and rebase.autostash set' '
+	test_config rebase.autostash true &&
+	git reset --hard before-rebase &&
+	echo dirty >new_file &&
+	git add new_file &&
+	git pull --rebase . copy &&
+	test_cmp_rev HEAD^ copy &&
+	test "$(cat new_file)" = dirty &&
+	test "$(cat file)" = "modified again"
+'
+
 test_expect_success 'pull.rebase' '
 	git reset --hard before-rebase &&
 	test_config pull.rebase true &&