filemerge: do what the context __bytes__ does, but locally str() here is clearly the wrong thing, and I think the code is clearer when it doesn't just depend on the magic __{str,bytes}__ behavior. I decided to grep around for \sstr\( and see what low-hanging fruit that showed me. This was part of that hunt. That grep pattern still has some things worth exploring. Differential Revision: https://phab.mercurial-scm.org/D2442