tests/test-filelog.py.out

transaction: add releasefn to notify the end of a transaction scope

'releasefn' is used by subsequent patch, to do appropriate action
according to the result of it at the end of a transaction scope.

To ensure that 'releasefn' is invoked only once, this patch invokes it
after assignment 'self.journal = None', because such assignment
prevents from invoked 'transaction._abort()' again via '__del__()'.

    def __del__(self):
        if self.journal:
            self._abort()

ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.