blame: avoid "diff -u0".

diff --git a/sha1_name.c b/sha1_name.c
index fa85d8a88d31219cef5bed195044327459f9162b..d67de18ba5f5aa1f5b3dd1c5c81e75618d12e330 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -186,16 +186,18 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 
 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 {
-       int status;
+       int status, is_null;
        static char hex[41];
 
+       is_null = !memcmp(sha1, null_sha1, 20);
        memcpy(hex, sha1_to_hex(sha1), 40);
        if (len == 40)
                return hex;
        while (len < 40) {
                unsigned char sha1_ret[20];
                status = get_short_sha1(hex, len, sha1_ret, 1);
-               if (!status) {
+               if (!status ||
+                   (is_null && status != SHORT_NAME_AMBIGUOUS)) {
                        hex[len] = 0;
                        return hex;
                }