t3508: add check_head_differs_from() helper function and use it

diff --git a/diffcore-delta.c b/diffcore-delta.c
index e670f8512558c38d9a9d6e754cfc609b042b1195..7cf431d261f9a35679ead7c8acda15aecdb8720d 100644 (file)
--- a/diffcore-delta.c
+++ b/diffcore-delta.c
@@ -201,10 +201,15 @@ int diffcore_count_changes(struct diff_filespec *src,
                while (d->cnt) {
                        if (d->hashval >= s->hashval)
                                break;
+                       la += d->cnt;
                        d++;
                }
                src_cnt = s->cnt;
-               dst_cnt = d->hashval == s->hashval ? d->cnt : 0;
+               dst_cnt = 0;
+               if (d->cnt && d->hashval == s->hashval) {
+                       dst_cnt = d->cnt;
+                       d++;
+               }
                if (src_cnt < dst_cnt) {
                        la += dst_cnt - src_cnt;
                        sc += src_cnt;
@@ -213,6 +218,10 @@ int diffcore_count_changes(struct diff_filespec *src,
                        sc += dst_cnt;
                s++;
        }
+       while (d->cnt) {
+               la += d->cnt;
+               d++;
+       }
 
        if (!src_count_p)
                free(src_count);