vfs: use repo.wvfs.unlinkpath

policy: try and always have a bytes for module policy debuginstall now runs cleanly in Python 3.

init: zstd is already python3-ready, so don't run it through our importer

config: guard against setconfig specifying unicode values on py3 This was leading to some difficult to trace problems because the values were set in one place, but then blew up much later in the program. Exploding violently with an assertion seems reasonable here.

dispatch: enforce bytes when converting boolean flags to config items This fixes --verbose on Python 3.

py3: add a test that proves %include and missing-extension code works

extensions: tapdance to get reasonable import error formatting I'm not thrilled with this, but it seems to work.

rebase: abort if *any* commit in rebase set is public

merge with stable

httpconnection: rename config to groups Because that is what it is.