Now that a job branch list can be a list of dictionaries, the autojob
directive can hit this error:
variant = ', '.join(branches)
TypeError: sequence item 0: expected str instance, dict found
Handle this by serializing the dictionaries with (str) so that we get
something printable. It's not going to be pretty, but the old regexes
weren't either.
Change-Id: I9c0b242a8993760a7b7b27bbf231550c03cde183