test_cmp: do not use "diff -u" on platforms that lack one

diff --git a/fsck.c b/fsck.c
index 511b82cba9977c14d6dcba5efbd6d38591d3aacc..89278c1459d36a3e2b718661ca71483522f587fd 100644 (file)
--- a/fsck.c
+++ b/fsck.c
@@ -229,7 +229,7 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
        struct commit_graft *graft;
        int parents = 0;
 
-       if (!commit->date)
+       if (commit->date == ULONG_MAX)
                return error_func(&commit->object, FSCK_ERROR, "invalid author/committer line");
 
        if (memcmp(buffer, "tree ", 5))