Inzwischen bin ich sehr zufrieden mit vcprompt,
bzw dem OSX freundlicheren fork davon:

bitbucket.org/gward/vcprompt/overview

usage: vcprompt [-h] [-d] [-f FORMAT]
FORMAT (default="[%n:%b%m%u] ") may contain:
 %b  show branch
 %r  show revision
 %u  show unknown
 %m  show modified
 %n  show VC name
 %%  show '%'

If a percent sign is followed by text in a pair brackets
('[xxx]') a default can be specified.
Environment Variables:
 VCPROMPT_FORMAT