Merge branch 'fr/sequencer-fail-with-not-one-upon-no-ff'

* fr/sequencer-fail-with-not-one-upon-no-ff:
sequencer: signal failed ff as an aborted, not a conflicted merge

diff --cc sequencer.c
index 0a80c58d1194c3476dfd2861a98fbd08610597a3,b087e121b4c87d1475dedc6a9de3fb3fdb231007..923047459bd3079da74245f2a0185ec437c9e8cd
--- 1/sequencer.c
--- 2/sequencer.c
+++ b/sequencer.c
@@@ -278,15 -278,11 +278,15 @@@ static int fast_forward_to(const unsign
  
        read_cache();
        if (checkout_fast_forward(from, to, 1))
-               exit(1); /* the callee should have complained already */
+               exit(128); /* the callee should have complained already */
        ref_lock = lock_any_ref_for_update("HEAD", unborn ? null_sha1 : from,
                                           0, NULL);
 +      if (!ref_lock)
 +              return error(_("Failed to lock HEAD during fast_forward_to"));
 +
        strbuf_addf(&sb, "%s: fast-forward", action_name(opts));
        ret = write_ref_sha1(ref_lock, to, sb.buf);
 +
        strbuf_release(&sb);
        return ret;
  }