uncommit: convert _fixdirstate() into _movedirstate()
_fixdirstate() already also updates to the given commit, so let's
rename it to _movedirstate(). Also update the documentation and drop
the unnecessary "curctx" argument, since that should always be
repo['.'].
Differential Revision: https://phab.mercurial-scm.org/D6117
#require docutils gettext
$ $TESTDIR/check-gendoc sv
checking for parse errors