shortest: make isrev() a top-level function I'm going to add another caller in the next patch. Differential Revision: https://phab.mercurial-scm.org/D4040

shortest: cache disambiguation revset This makes it actually useful. In compared the time in my hg repo with 69.6k revisions and with a disambiguation revset of "not public()" that matches 563 visible revisions. I ran "time hg log -T '{shortest(node1,)}' -r 0:1000" (no revisions within the revset in that revision range). Before this patch, it took 57s and after it took 0.7s. Differential Revision: https://phab.mercurial-scm.org/D4039

index: don't allow index[len(index)] to mean nullid Now everything else has been cleaned up and we can drop support for getting the nullid from the end of the index (from *past* the end actually, since we reduced the length in the previous patch). Differential Revision: https://phab.mercurial-scm.org/D4023

index: don't include nullid in len() I suspect the reason the nullid is in the index in the last position is that it lets index[i] for regular revision number, even when index was just a regular Python list. An alternative solution would have been to reserve revision number 0 for the null revision. I don't know why that wasn't done. Now that we have classes backing the index, we can easily make index[-1] get the nullid without having to put it last in the list and including it in the len(). This patch just hides the nullid -- it will still be accessible at index[len(index)]. I realize that this will be annoying when checking out across this commit for debugging (including bisection). Differential Revision: https://phab.mercurial-scm.org/D4022