Merge branch 'rs/ref-transaction-1'
The second batch of the transactional ref update series.
* rs/ref-transaction-1: (22 commits)
update-ref --stdin: pass transaction around explicitly
update-ref --stdin: narrow scope of err strbuf
refs.c: make delete_ref use a transaction
refs.c: make prune_ref use a transaction to delete the ref
refs.c: remove lock_ref_sha1
refs.c: remove the update_ref_write function
refs.c: remove the update_ref_lock function
refs.c: make lock_ref_sha1 static
walker.c: use ref transaction for ref updates
fast-import.c: use a ref transaction when dumping tags
receive-pack.c: use a reference transaction for updating the refs
refs.c: change update_ref to use a transaction
branch.c: use ref transaction for all ref updates
fast-import.c: change update_branch to use ref transactions
sequencer.c: use ref transactions for all ref updates
commit.c: use ref transactions for updates
replace.c: use the ref transaction functions for updates
tag.c: use ref transactions when doing updates
refs.c: add transaction.status and track OPEN/CLOSED
refs.c: make ref_transaction_begin take an err argument
...