localrepo: pass hook argument txnid to pretxnopen hooks Before this patch, hook argument `txnid` isn't passed to `pretxnopen` hooks, even though `hooks` section of `hg help config` describes so. ``pretxnopen`` Run before any new repository transaction is open. The reason for the transaction will be in ``$HG_TXNNAME`` and a unique identifier for the transaction will be in ``HG_TXNID``. A non-zero status will prevent the transaction from being opened.