fast-import maint fixes

The following changes since commit 7ca055f75ad7ffd2251d4b607fbb86d7bcfd77c7:
  Stephan Springl (1):
        Use git-for-each-ref to check whether the origin branch exists.

are available in the git repository at:

  repo.or.cz:/srv/git/git/fastimport.git maint

Shawn O. Pearce (2):
      Refactor fast-import branch creation from existing commit
      Fix possible coredump with fast-import --import-marks

Simon Hausmann (2):
      fast-import: Fix uninitialized variable
      fast-import: Fix crash when referencing already existing objects

 fast-import.c          |   67 ++++++++++++++++++++++++++---------------------
 t/t9300-fast-import.sh |   29 ++++++++++++++++++++
 2 files changed, 66 insertions(+), 30 deletions(-)

These are built on top of Junio's maint, and should be merged there, as they fix coredumps when documented features are actually used.

:-(