Re: [PATCH 2/2] format-patch: introduce format.defaultTo

Ramkumar Ramachandra [off-list ref] writes:

A very common workflow for preparing patches involves working off a
topic branch and generating patches against 'master' to send off to the
maintainer. However, a plain

  $ git format-patch -o outgoing

is a no-op on a topic branch,...

Two points.

 - why is a single branch name sufficient?

 - is it a better option to simply default to @{u}, if one exists,
   instead of failing?