merge-base: teach "--fork-point" mode

diff --git a/refs.c b/refs.c
index 43022066499ffaf828ac31e82b77f53539bc232d..a3f2302292190b147a1cee092a26d47ace7a1228 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -2174,11 +2174,14 @@ int lock_packed_refs(int flags)
 {
        struct packed_ref_cache *packed_ref_cache;
 
-       /* Discard the old cache because it might be invalid: */
-       clear_packed_ref_cache(&ref_cache);
        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
                return -1;
-       /* Read the current packed-refs while holding the lock: */
+       /*
+        * Get the current packed-refs while holding the lock.  If the
+        * packed-refs file has been modified since we last read it,
+        * this will automatically invalidate the cache and re-read
+        * the packed-refs file.
+        */
        packed_ref_cache = get_packed_ref_cache(&ref_cache);
        packed_ref_cache->lock = &packlock;
        /* Increment the reference count to prevent it from being freed: */