rhg: add support for ignoring all extensions Some workflows just want what `rhg` does and don't care about any extensions, this makes it easier. Differential Revision: https://phab.mercurial-scm.org/D12385

To run the tests, do:

cd tests/
python run-tests.py

See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.