fix: again allow formatting the working copy while merging I forgot about unfinished merges (I think I was thinking only about unfinished merge conflicts) when I wrote https://phab.mercurial-scm.org/D11209. As a coworker (hg contributor dploch) reported to me, this led to `hg fix --working-dir` failing when you have an uncommitted merge. The fix is trivial: just move the assertion to just before the call to `scmutil.movedirstate()` where it actually matters. Differential Revision: https://phab.mercurial-scm.org/D11376