D8232: phabricator: add a helper function to convert DREVSPECs to a DREV dict list

[Yuya Nishihara]

> > +def _getdrevs(ui, stack, *specs):
> > +    """convert user supplied DREVSPECs into "Differential Revision" dicts
> > +
> > +    See ``hg help phabread`` for how to specify each DREVSPEC.
> > +    """
> > +    if len(*specs) > 0:
>               ^^^^^^
> Fixed bad argument expansion since I had to rebase this. Please let me
> know if that's wrong.

Never mind. Maybe `specs` is a list containing a single list, in which case,
the code is valid.