watching related units

[William Reade]

On Sat, 2012-06-09 at 19:42 +0200, William Reade wrote:
> I have a bit of a problem

...which I think is now dealt with, after a few rounds of stripping away
unnecessary complexity. Funny how that works out...

However, I am now somewhat blocked on reviews. I have 2 pipelines open:

* version-watcher: https://codereview.appspot.com/6305070/
* unit-relation-watcher: https://codereview.appspot.com/6300069/

...and:

* convenient-relation-interface: https://codereview.appspot.com/6303060/
* add-unit-relation: https://codereview.appspot.com/6304057/

...and the next branch I want to push (related-units-watcher) depends on
both add-unit-relation and unit-relation-watcher. The *-watcher pipeline
should be uncontroversial and easy to review; I would greatly appreciate
prompt attention to those CLs, so that I can give the upcoming branch a
clean parent.

Cheers
William