I would suggest putting higher use parameters first to allow specifying them w/o needing to use intervening keywords, for example:

    def __call__(self, cmd, args=None, stdin=None, verbose=False, timeout=60):

That enables:

    dockercmdr('run', ['-i', fqin, 'bash'], mypipe)

Whereas, as written if I want to pass a stdin pipe, I also have to specify a timeout so I cann't use the default value (or have to hard code it, or use keyword args).  Anyway, it's a small touch, arguably keywords should probably just be used most of the time to avoid future param. order problems.