phabricator: abort if phabsend gets empty revs
Previously we didn't abort. Now we abort if revs is empty. This is
consistent with "hg export" behavior. Maybe "return 1" is also a reasonable
behavior, but that's inconsistent with the existing "hg export".
.. Common link and substitution definitions.
.. |hg(1)| replace:: **hg**\ (1)
.. _hg(1): hg.1.html
.. |hgrc(5)| replace:: **hgrc**\ (5)
.. _hgrc(5): hgrc.5.html
.. |hgignore(5)| replace:: **hgignore**\ (5)
.. _hgignore(5): hgignore.5.html