py3: suppress the return value of write() in tests/test-subrepo-missing.t
write() on Python 3 returns a value whereas does not return anything on Python 2.
So we need to supress the value.
Differential Revision: https://phab.mercurial-scm.org/D3283
py3: add b'' prefixes in tests/test-linerange.py
This makes the test pass on Python 3.
# skip-blame because just b'' prefixes
Differential Revision: https://phab.mercurial-scm.org/D3282