def find_revision_number(self, revision=None):
<EOL>self.create()<EOL>revision = revision or self.default_revision<EOL>output = self.context.capture('<STR_LIT>', '<STR_LIT:id>', '<STR_LIT>' % revision, '<STR_LIT>').rstrip('<STR_LIT:+>')<EOL>if not output.isdigit():<EOL><INDENT>msg = "<STR_LIT>"<EOL>raise EnvironmentError(msg)<EOL><DEDENT>return int(output)<EOL>
Find the local revision number of the given revision.