tests: adjust to the new format in pyflakes output
According to the pyflakes' NEWS.rst, the default output format changed
recently:
2.2.0 (2020-04-08)
- Include column information in error messages
So the lines now read:
contrib/perf.py:149:15 undefined name 'xrange'
mercurial/hgweb/server.py:427:13 undefined name 'reload'
mercurial/util.py:2862:24 undefined name 'file'
This is a graft of a similar fix that ended up on default.
Differential Revision: https://phab.mercurial-scm.org/D8630
== New Features ==
== New Experimental Features ==
== Backwards Compatibility Changes ==
== Internal API Changes ==