localrepo: clear _filecache earlier to really force reloading (issue3462)
ce0ad184f489 attempted to force the filecaches in localrepo to reload
everything after a rollback. But simply clearing _filecache isn't enough,
invalidate() needs to be called before/after. localrepo._rollback calls
invalidate() already, so we clear the map right afterwards which ensures
everything will be reread.
$ echo '[Section]' >> $HGRCPATH
$ echo 'KeY = Case Sensitive' >> $HGRCPATH
$ echo 'key = lower case' >> $HGRCPATH
$ hg showconfig Section
Section.KeY=Case Sensitive
Section.key=lower case