tags: show how hg behaves if a tags cache entry is truncated
I'm seeing an error of this form in production on the order of once a
month. I'm not sure how it happens, but I suspect interrupting a pull
might result in half written cache entries.
Differential Revision: https://phab.mercurial-scm.org/D8094
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state