convert: workaround for cvsps.cache under Windows In non-cygwin environment, cvsps fails to create its cache directory and redirect its output to stderr. Just ignore the error and capture stderr as well.

To run the tests, do:

cd tests/
python run-tests.py

See http://www.selenic.com/mercurial/wiki/index.cgi/WritingTests for
more information on writing tests.