py3: raw stringify various things in the LFS server module Some of this is based on code written by Augie. I'm slightly unsure if these are the correct pycompat bytes <-> str conversion methods.

py3: add b'' prefixes to the LFS server module There are a ton of these changes in the blobstore, as well as r'' prefixing. So separating these out hopefully makes review easier. # skip-blame for b'' prefixing

py3: add b'' and r'' prefixes to LFS tests

py3: more tests from the ratchet Differential Revision: https://phab.mercurial-scm.org/D5730

dispatch: unify handler of IOError and OSError These exceptions were merged in Python 3.

dispatch: quote filename in IOError as well It's explicitly added for OSError at 720308f741cb "dispatch: show empty filename in OSError aborts". Let's do the same for IOError.

dispatch: add inline comment about possible IOError subtypes It's hard to tell which "if" would handle which exception.

convert: print exception message directly Otherwise the default repr() implementation will b'' prefix the returned str on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5729

crecord: always return a str from uihunk.__repr__ Otherwise Python 3 complains about it returning bytes. Differential Revision: https://phab.mercurial-scm.org/D5728

tests: handles bytes/str mismatch in test-commit-interface-curses.t This fixes various test failures on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5727