1 files changed, 17 insertions, 0 deletions
diff --git a/refs.c b/refs.c
index b3860a9e33..beb49fb297 100644
--- a/refs.c
+++ b/refs.c
@@ -1702,6 +1702,23 @@ int create_symref(const char *ref_target, const char *refs_heads_master,
 				  refs_heads_master, logmsg);
 }
 
+int ref_update_reject_duplicates(struct string_list *refnames,
+				 struct strbuf *err)
+{
+	int i, n = refnames->nr;
+
+	assert(err);
+
+	for (i = 1; i < n; i++)
+		if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
+			strbuf_addf(err,
+				    "multiple updates for ref '%s' not allowed.",
+				    refnames->items[i].string);
+			return 1;
+		}
+	return 0;
+}
+
 int ref_transaction_prepare(struct ref_transaction *transaction,
 			    struct strbuf *err)
 {