Merge branch 'ps/avoid-unnecessary-hook-invocation-with-packed-refs'

Because a deletion of ref would need to remove it from both the
loose ref store and the packed ref store, a delete-ref operation
that logically removes one ref may end up invoking ref-transaction
hook twice, which has been corrected.

* ps/avoid-unnecessary-hook-invocation-with-packed-refs:
  refs: skip hooks when deleting uncovered packed refs
  refs: do not execute reference-transaction hook on packing refs
  refs: demonstrate excessive execution of the reference-transaction hook
  refs: allow skipping the reference-transaction hook
  refs: allow passing flags when beginning transactions
  refs: extract packed_refs_delete_refs() to allow control of transaction

refs/refs-internal.h

@@ -213,6 +213,7 @@ struct ref_transaction {
 	size_t nr;
 	enum ref_transaction_state state;
 	void *backend_data;
+	unsigned int flags;
 };
 
 /*