def find_revision_id(self, revision=None):
<EOL>self.create()<EOL>revision = revision or self.default_revision<EOL>output = self.context.capture(<EOL>'<STR_LIT>', '<STR_LIT>', '<STR_LIT>' % revision,<EOL>'<STR_LIT>', '<STR_LIT>',<EOL>)<EOL>if not output:<EOL><INDENT>msg = "<STR_LIT>"<EOL>raise ValueError(msg)<EOL><DEDENT>return output<EOL>
Find the global revision id of the given revision.