[MERGE] Upgrade ConfigObj to 4.6.0

[Matt Nordhoff]

John Arbash Meinel wrote:
> Matt Nordhoff wrote:
>> [Sorry about not including the diff in the merge directive but I've
>> tried to send this message twice and it hasn't gone through, so now I'm
>> trying this. If it turns out that they're being held by Mailman, um,
>> sorry for the duplicates.]
>> 
>> Hi,
>> 
>> This patch upgrades Bazaar's bundled copy of ConfigObj from 4.5.2 to 4.6.0.
>> 
>> ConfigObj has made some changes to the documentation files, getting rid
>> of the ones Bazaar versioned, so I just deleted them all since they
>> aren't necessary anyway.
>> 
>> There's some extra noise in the patch because I changed "has_key" to
>> "in" without noticing that I hadn't bothered to make that change to
>> 4.5.2. Sorry about that. I can revert it again, but I don't see any need
>> to. [Plus it would be a pain. :-P ]
>> 
>> The test suite passes, but I haven't tried running with it or anything.
>> I also haven't measured performance.
>> 
> 
> BB:comment
> 
> I'm not specifically against upgrading, but do we know if we gain any
> benefit from this?
> 
> John
> =:->

Hmm. Honestly, I don't think so. The only two changes we care about are
the hasattr/getattr and Exception.message things, which we had already
edited in anyway.

ConfigObj's getattr code uses a sentinel object() as the default value,
while we used None, and it's possible using None could've conceivably
caused issues, but I'm really reaching here.

I figure that 4.6.0 is demonstrably 0.1% better -- e.g. deleting the
docs probably saves 100 KB of disk space, and configobj.py is slightly
smaller as well -- but whether it's worth the risk of new bugs is an
open question.

The main reason to upgrade is really just to keep current. :-\
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