Re: [PATCH v8 15/44] commit.c: use ref transactions for updates

Ronnie Sahlberg wrote:

Change commit.c to use ref transactions for all ref updates.
Make sure we pass a NULL pointer to ref_transaction_update if have_old
is false.

Once ref_transaction_begin() and ref_transaction_update() set err,
this will always have a reasonable message to print in die().

Reviewed-by: Jonathan Nieder <redacted>