tests: allow [Errno] in output
I'm not sure why, but my system is printing "[Errno -5]" before
the "No address associated with hostname" message. I suspect a
modern version of Python improved errno tracking or something.
Add an "[Errno ...]" pattern as optional output to make the test
pass.
Differential Revision: https://phab.mercurial-scm.org/D1958
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.