[PATCH 0/5] ref-transactions-rename

This patch series adds support for using transactions and atomic renames. It focuses on what needs to be done in order to support fully atomic and rollbackable renames that may or may not involve name conflicts.

By performing the actual delete old/create new via a single operation to the packed refs file this process will also appear as an atomic change for any external observers.

(While this series is "short" it contains a very important change where we start performing ref changes as operations inside a locked packed refs file instead of as discreete operations of loose ref files. This approach will be extended in the next patch series where we will start using it also to make multi-ref creations/updates become fully atomic for external observers.)

This series is built on iand depend on the previous reflog series:
  * rs/ref-transaction-reflog (2014-07-23) 15 commits
   - refs.c: allow deleting refs with a broken sha1
   - refs.c: remove lock_any_ref_for_update
   - refs.c: make unlock_ref/close_ref/commit_ref static
   - refs.c: rename log_ref_setup to create_reflog
   - reflog.c: use a reflog transaction when writing during expire
   - refs.c: allow multiple reflog updates during a single transaction
   - refs.c: only write reflog update if msg is non-NULL
   - refs.c: add a flag to allow reflog updates to truncate the log
   - refs.c: add a transaction function to append a reflog entry
   - lockfile.c: make hold_lock_file_for_append preserve meaningful errno
   - refs.c: add a function to append a reflog entry to a fd
   - refs.c: add a new update_type field to ref_update
   - refs.c: rename the transaction functions
   - refs.c: make ref_transaction_delete a wrapper for ref_transaction_update
   - refs.c: make ref_transaction_create a wrapper to ref_transaction_update
   (this branch uses rs/ref-transaction and rs/ref-transaction-1.)

Ronnie Sahlberg (5):
  refs.c: allow passing raw git_committer_info as email to
    _update_reflog
  refs.c: return error instead of dying when locking fails during
    transaction
  refs.c: use packed refs when deleting refs during a transaction
  refs.c: update rename_ref to use a transaction
  refs.c: rollback the lockfile before we die() in repack_without_refs

 builtin/remote.c  |  13 +-
 refs.c            | 369 +++++++++++++++++++++++++++++-------------------------
 refs.h            |   1 +
 t/t3200-branch.sh |   7 --
 4 files changed, 210 insertions(+), 180 deletions(-)