The attach_mock in the following code sample fails silently:

    >>> from mock import patch, Mock
    >>> p = patch('requests.get', autospec=True)
    >>> manager = Mock()
    >>> manager.attach_mock(p.start(), 'requests_get')
    >>> import requests
    >>> requests.get('https://google.com')
    <MagicMock name='get()' id='4472381392'>
    >>> manager.mock_calls
    []
    >>> p.stop()
    >>> manager.mock_calls
    []

It seems this would be a useful use-case, especially given that this code would work as-expected if 'requests.get' in the second line were replaced with a path to a class.