test-check-help: fix to work on Windows
The initial problem was `hg files` prints paths with '\', which gets removed
when piped (scanhelptopics.py failed to open 'hgext__init__.py'). Then, xargs
was invoking `hg help` with 'backout\r (esc)', which setting binary mode
prevents.
#require test-repo pylint hg10
Run pylint for known rules we care about.
-----------------------------------------
There should be no recorded failures; fix the codebase before introducing a
new check.
Current checks:
- W0102: no mutable default argument
$ touch $TESTTMP/fakerc
$ pylint --rcfile=$TESTTMP/fakerc --disable=all \
> --enable=W0102 --reports=no \
> mercurial hgext hgext3rd