Analysis of Python 2.7 support in Natty

[Krzysztof Klimonda]

On Thu, 2011-02-03 at 15:56 -0500, Barry Warsaw wrote:
[...]
> If necessary, we can solve the LTS upgrade problem similar to the way we
> solved it for Lucid; we create an official PPA with Python 2.6 and port over
> the stack required by services such as Launchpad.  3rd parties still requiring
> Python 2.6, could create their own PPA, dependent on ours, and add whatever
> packages they need to the former.
> 
> Of course, we could also keep Python 2.6 and Python 2.7 until after 12.04.
> 
> There seems to be lots of folks both for and against removal of Python 2.6.
> It's worth discussion here, but we need to make a final decision for Natty by
> feature freeze later this month.

I'm on the fence regarding this issue. On one hand I have few issues
with removal of Python 2.6 from natty. On the other hand, there are good
reasons to do that.

I have two main issues with dropping Python 2.6 from natty, or with
moving it to the official PPA.
 First, as there is no way to test all the python applications for the
compatibility with 2.7, we are risking that we'll ship some broken
software. It's not an issue for main, where there are many people
looking at, and testing all the packages, but in the universe, or rather
the "unseeded", world we may not catch all problems before the release.
As Far as I Remember during the last transition there were bugs showing
up on the LP even after the release, and the fastest and least-invasive
way of fixing them was to force package to use Python 2.5. This time
we'll have to actually investigate, and patch them all. It may yet again
cause people to raise concerns about the quality of the software we are
providing.
From your experience with main, were there many issues with
backward-incompatible changes in Python 2.7?

 The second issue is of a different matter - I just don't feel that we
should bless PPAs as official, as long as there is no way to distinguish
them from the "unofficial" ones in the Launchpad interface. They are
called "personal" for a reason, and every time they are used for the
official stuff, sanctioned by developers we are adding to the confusion.
Damn, there is even a fine print on each PPA's page: "You can update
your system with unsupported packages from this untrusted PPA". And if
we say "hey, this PPA is actually supported by us" then how are users
supposed to distinguish between "supported unsupported" PPAs and the
"unsupported unsupported" PPAs. Poorly maintained PPAs are a source of
many issues raised by out users.

On the other hand, with the introduction of Unity 2D which is going to
pull Qt, and few other libraries onto the CD, it does seem a little...
"unsocial" to ship ~10MB of libraries because user may install Python
2.6 in the future.. 10MB equals one language pack, that would have to be
dropped from the CD.

If 11.04 were the LTS, I'd most likely be against dropping Python 2.6
from the archive, but I don't know if we can actually carry 2.6 all the
way to the next LTS. We may end up having the same discussion in 6
months, when we run out of space on CD and can't cut anything else off.
If it's the alternative then dropping 2.6 now leaves us with more time
to work on any unexpected issues.

Cheers,
  KK
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