tests: test utils.lookup_option()

queue: don't use full path to config file (likely to be different in isolation)

queue: worker queue for running checks

checker: set LC_ALL for git

checker: use absolute imports

checker: take commit to update to as an optional argument

queue: git hooks naturally don't provide topological branch heads

queue: add incoming queue handler

queue: data is a string, we need item (TypeError)

queue: work around parse_command_line() ignoring the first argument