Requiring Python 2.7 to Build the Tree

[Gregory Szorc]

I originally sent this as a reply to the "Minimum Required Python
Version" thread. Per request, I'm reposting as a new topic so it doesn't
go unnoticed. We will also likely discuss this at the engineering
meeting tomorrow. SeaMonkey has also requested an additional week to
switch things over, so there will likely be no action until after the
weekend.

Original message follows.

---

The bump to Python 2.6 seemed to go OK. So, I think it's time to finish
the transition and bump the minimum to Python 2.7.

Per the previous discussion on this list, I don't believe we have any
outstanding objections. So, I propose we move forward with this as soon
as we have confirmation that all builders are on Python 2.7.

https://bugzilla.mozilla.org/show_bug.cgi?id=804865 is tracking bumping
the /build/ requirement to Python 2.7. Some tests will still be running
on older Python. But, I believe everybody is on board with transitioning
everything to 2.7. So, we should pretend this transition effectively
means we can stop supporting 2.6 and below everywhere in the tree as
soon as 2.7 is deployed everywhere.

If there are any objections, please voice them now.

Gregory