branch: exit status now reflects if branch listing finds an error

If some refs could not be read when listing branches, this can now be
observed in the exit status of the "git branch" command.

Signed-off-by: Simo Melenius <simo.melenius@iki.fi>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/branch.c

@@ -257,9 +257,15 @@ static char *resolve_symref(const char *src, const char *prefix)
 	return xstrdup(dst);
 }
 
+struct append_ref_cb {
+	struct ref_list *ref_list;
+	int ret;
+};
+
 static int append_ref(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
 {
-	struct ref_list *ref_list = (struct ref_list*)(cb_data);
+	struct append_ref_cb *cb = (struct append_ref_cb *)(cb_data);
+	struct ref_list *ref_list = cb->ref_list;
 	struct ref_item *newitem;
 	struct commit *commit;
 	int kind, i;
@@ -293,8 +299,10 @@ static int append_ref(const char *refname, const unsigned char *sha1, int flags,
 	commit = NULL;
 	if (ref_list->verbose || ref_list->with_commit || merge_filter != NO_FILTER) {
 		commit = lookup_commit_reference_gently(sha1, 1);
-		if (!commit)
-			return error("branch '%s' does not point at a commit", refname);
+		if (!commit) {
+			cb->ret = error("branch '%s' does not point at a commit", refname);
+			return cb->ret;
+		}
 
 		/* Filter with with_commit if specified */
 		if (!is_descendant_of(commit, ref_list->with_commit))
@@ -484,9 +492,10 @@ static void show_detached(struct ref_list *ref_list)
 	}
 }
 
-static void print_ref_list(int kinds, int detached, int verbose, int abbrev, struct commit_list *with_commit)
+static int print_ref_list(int kinds, int detached, int verbose, int abbrev, struct commit_list *with_commit)
 {
 	int i;
+	struct append_ref_cb cb;
 	struct ref_list ref_list;
 
 	memset(&ref_list, 0, sizeof(ref_list));
@@ -496,7 +505,9 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev, str
 	ref_list.with_commit = with_commit;
 	if (merge_filter != NO_FILTER)
 		init_revisions(&ref_list.revs, NULL);
-	for_each_rawref(append_ref, &ref_list);
+	cb.ref_list = &ref_list;
+	cb.ret = 0;
+	for_each_rawref(append_ref, &cb);
 	if (merge_filter != NO_FILTER) {
 		struct commit *filter;
 		filter = lookup_commit_reference_gently(merge_filter_ref, 0);
@@ -527,6 +538,8 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev, str
 	}
 
 	free_ref_list(&ref_list);
+
+	return cb.ret;
 }
 
 static void rename_branch(const char *oldname, const char *newname, int force)
@@ -679,7 +692,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	if (delete)
 		return delete_branches(argc, argv, delete > 1, kinds);
 	else if (argc == 0)
-		print_ref_list(kinds, detached, verbose, abbrev, with_commit);
+		return print_ref_list(kinds, detached, verbose, abbrev, with_commit);
 	else if (rename && (argc == 1))
 		rename_branch(head, argv[0], rename > 1);
 	else if (rename && (argc == 2))