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).
$ echo '[Section]' >> $HGRCPATH
$ echo 'KeY = Case Sensitive' >> $HGRCPATH
$ echo 'key = lower case' >> $HGRCPATH
$ hg showconfig Section
Section.KeY=Case Sensitive
Section.key=lower case