[PATCH v3 0/4] Add an option to git-format-patch to record base tree info

V3 mainly improves the implementation according to Junio's comments, Changes vs v2 include:

 - Remove the unnecessary output line "** base-commit-info **".
 
 - Improve the traverse logic to handle not only linear topology, but more
   general cases, it will start revision walk by setting the starting points
   of the traversal to all elements in the rev list[], and skip the ones in 
   list[], only grab the patch-ids of prerequisite patches.

 - If --base=auto is set, it will get merge base of upstream and rev range
   we specified and use it as base commit. If there is no upstream, we just
   error out and suggest to use set-upstream-to to track a remote branch
   as upstream.

v1 can be found here: http://article.gmane.org/gmane.comp.version-control.git/286873 v2 can be found here: http://article.gmane.org/gmane.comp.version-control.git/289603

Xiaolong Ye (4):
  patch-ids: make commit_patch_id() a public helper function
  format-patch: add '--base' option to record base tree info
  format-patch: introduce --base=auto option
  format-patch: introduce format.base configuration

 Documentation/git-format-patch.txt |  31 ++++++++++
 builtin/log.c                      | 119 +++++++++++++++++++++++++++++++++++++
 patch-ids.c                        |   2 +-
 patch-ids.h                        |   2 +
 4 files changed, 153 insertions(+), 1 deletion(-)