refs_ref_iterator_begin(): don't check prefixes redundantly

The backend already correctly restricts its output to references whose
names start with the prefix. By passing the prefix again to
`prefix_ref_iterator`, we were forcing that iterator to do redundant
prefix comparisons. So set it to the empty string.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index 8af9641aa17e68bfcf9d5e042cb1116995a99042..8494b1f20d5a160bfe0749517898e76259bafc71 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1247,7 +1247,13 @@ struct ref_iterator *refs_ref_iterator_begin(
        struct ref_iterator *iter;
 
        iter = refs->be->iterator_begin(refs, prefix, flags);
-       iter = prefix_ref_iterator_begin(iter, prefix, trim);
+
+       /*
+        * `iterator_begin()` already takes care of prefix, but we
+        * might need to do some trimming:
+        */
+       if (trim)
+               iter = prefix_ref_iterator_begin(iter, "", trim);
 
        return iter;
 }