largefiles: test reverting largefiles (coverage creeping ever upwards)
This reveals a small bug: revert reports "reverting .hglf/largefile"
when it really should report "reverting largefile". I don't see an
easy fix, though (short of using ui.pushbuffer() to interfere with
revert's output).
Minimal hgk check
$ echo "[extensions]" >> $HGRCPATH
$ echo "hgk=" >> $HGRCPATH
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Am adda
adding a
$ hg debug-cat-file commit 0
tree a0c8bcbbb45c
parent 000000000000
author test 0 0
committer test 0 0
revision 0
branch default
adda