1 files changed, 24 insertions, 9 deletions
diff --git a/refs.c b/refs.c
index d80efd58f0..2efa6bcc5c 100644
--- a/refs.c
+++ b/refs.c
@@ -2116,26 +2116,38 @@ int peel_iterated_oid(struct repository *r, const struct object_id *base, struct
 int refs_update_symref(struct ref_store *refs, const char *ref,
 		       const char *target, const char *logmsg)
 {
-	return refs_update_symref_extended(refs, ref, target, logmsg, NULL);
+	return refs_update_symref_extended(refs, ref, target, logmsg, NULL, 0);
 }
 
 int refs_update_symref_extended(struct ref_store *refs, const char *ref,
 		       const char *target, const char *logmsg,
-		       struct strbuf *referent)
+		       struct strbuf *referent, int create_only)
 {
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
-	int ret = 0;
+	int ret = 0, prepret = 0;
 
 	transaction = ref_store_transaction_begin(refs, &err);
-	if (!transaction ||
-	    ref_transaction_update(transaction, ref, NULL, NULL,
-				   target, NULL, REF_NO_DEREF,
-				   logmsg, &err) ||
-	    ref_transaction_prepare(transaction, &err)) {
+	if (!transaction) {
+	error_return:
 		ret = error("%s", err.buf);
 		goto cleanup;
 	}
+	if (create_only) {
+		if (ref_transaction_create(transaction, ref, NULL, target,
+					   REF_NO_DEREF, logmsg, &err))
+			goto error_return;
+		prepret = ref_transaction_prepare(transaction, &err);
+		if (prepret && prepret != TRANSACTION_CREATE_EXISTS)
+			goto error_return;
+	} else {
+		if (ref_transaction_update(transaction, ref, NULL, NULL,
+					   target, NULL, REF_NO_DEREF,
+					   logmsg, &err) ||
+			ref_transaction_prepare(transaction, &err))
+			goto error_return;
+	}
+
 	if (referent && refs_read_symbolic_ref(refs, ref, referent) == NOT_A_SYMREF) {
 		struct object_id oid;
 		if (!refs_read_ref(refs, ref, &oid)) {
@@ -2144,8 +2156,11 @@ int refs_update_symref_extended(struct ref_store *refs, const char *ref,
 		}
 	}
 
+	if (prepret == TRANSACTION_CREATE_EXISTS)
+		goto cleanup;
+
 	if (ref_transaction_commit(transaction, &err))
-		ret = error("%s", err.buf);
+		goto error_return;
 
 cleanup:
 	strbuf_release(&err);