Skip colon when an empty type is specified and writing a google docstring

[AWhetter]

Reading the following docstring

"""
Description

:return: A thing
:rtype: C{}
"""

results in the following Google docstring

"""Description

Returns:
     : A thing
"""

I would expect the colon to be skipped in the output because the type is empty.

[cbillingham]

Same situation for this one.
I get this output with the current version:

"""Description

Returns:
    C{}: A thing
"""

[AWhetter]

I can't reproduce this one again either. I'm not sure why it failed the first time.