tests: add xrange alias for test-pathencode.py

python3: another 3 tests whitelisted

repair: reliably obtain bytestr of node ids

bundles: turn nbchanges int into a bytestr using pycompat.bytestr Fixes some python 3 failures.

exchange: hit opargs with pycompat.strkwargs before **-ing it Fixes Python 3 problems.

revlog: update signature of dummy addgroup() in bundlerepo and unionrepo Per c8b6ed51386b, 2f5c45fe3a3b and 00e3f909907f.

py3: use 'surrogatepass' error handler to process U+DCxx transparently It's disallowed by default on Python 3. https://docs.python.org/3/library/codecs.html#error-handlers

py3: don't pass bytes to array.array()