Decode stdin and stdout rather than
joining 8-bit strings as unicode.
(Bug #750930)
Don't lock with a finally: call to unlock (just in case something bad happens)
- Add option to merge only one MP, and use web link where possible.
- Also exit when merging more than one branch
- Fix typo, exit when merge fails too.
Only trigger recipe builds when at least one branch of a merge succeeds
Change signature as requested by Paul in review.
Only trigger recipe builds when at least one branch of a merge succeeds.
Ensure that the log directory gets created if we can.

Add a bunch of tests to handle when we aren't actually able to
create the log directory.
Merge trunk.
Continue on LockContention errors while trying to merge.
Use .web_link when logging info about branches/merges so that they can be easily opened.
Merge the web_link change.
Merged one-at-a-time into lock-contention.
Log a message about an MP with a web link.
When starting up, make sure the logging directory exists before trying to log into it.
Add the option to only act on a single MP, useful when tarmac is used
with jenkins.
Ignore LockContention errors when trying to merge a branch.
Wrap branch and tree locks in a finally to guarantee the .unlock will be called
Fix the tests to run correctly again.
Remove the dependence on twisted trial.