* kn/ref-transaction-symref:
refs: remove `create_symref` and associated dead code
refs: rename `refs_create_symref()` to `refs_update_symref()`
refs: use transaction in `refs_create_symref()`
refs: add support for transactional symref updates
refs: move `original_update_refname` to 'refs.c'
refs: support symrefs in 'reference-transaction' hook
files-backend: extract out `create_symref_lock()`
refs: accept symref values in `ref_transaction_update()`
939d49e9bd