dirstate: make dirstate.write() callers pass transaction object to it Now, 'dirstate.write(tr)' delays writing in-memory changes out, if a transaction is running. This may cause treating this revision as "the first bad one" at bisecting in some cases using external hook process inside transaction scope, because some external hooks and editor process are still invoked without HG_PENDING and pending changes aren't visible to them. 'dirstate.write()' callers below in localrepo.py explicitly use 'None' as 'tr', because they can assume that no transaction is running: - just before starting transaction - at closing transaction, or - at unlocking wlock