tests/sitecustomize.py

wireproto: add a _calltwowaystream method on wirepeer

This method will be used by bundle2 pushes. It calls a command, feeds it with a
stream and receives another stream in reply.

Actual implementation for ssh and http will be done in later changesets.

try:
    import coverage
    getattr(coverage, 'process_startup', lambda: None)()
except ImportError:
    pass