Re: [PATCH v2 06/10] refs: skip collision checks in initial transactions

> While we generally cannot avoid the first check, the second check is
> superfluous in cases where the transaction is an initial one in an
> otherwise empty ref store. The check results in multiple ref reads as
> well as the creation of a ref iterator for every ref we're checking,
> which adds up quite fast when performing the check for many refs.
>
> Introduce a new flag that allows us to skip this check and wire it up in
> such that the backends pass it when running an initial transaction. This