I tweaked some code and ran a test a couple of revisions prior to the tip, accepting the changes.  I then did an update, but bailed on resolving the test conflicts because there were too many, and simply reran the test.  I totally forgot about the unmerged state until I tried updating elsewhere.  But in the meantime, it let me (evolve) amend, and `hg ci --amend` (with evolve disabled).  The working directory is clean (and summary agrees, though it notes one unresolved file, as does `hg resolve --list`).  Vanilla commit and update are both blocked.

I can see a selective amend (-I/-X/path) after an update being useful even if there are unresolved files, as long as the selected ones aren't unresolved.  But allowing an unresolved file to be amended feels like a bug.  If not, it should probably clear the unresolved state.