On Tuesday, August 19, 2014 08:02:37 AM Jeff Garzik wrote:
> It would be nice if the issues and git repo for Bitcoin Core were not
> on such a centralized service as github, nice and convenient as it is.

Assuming there is a problem with that usually is caused by using Git the wrong 
way or not knowing its capabilities. Nobody can modify / insert a commit 
before a GnuPG signed commit / tag without breaking the signature.
More detail at the bottom at [1], I am sparing you this here because I suspect 
you already know it and there is something more important I want to stress:

Bitcoin has currently 4132 forks on Github. This means that you can get 
contributions by pull requests from 4132 developers. That is a HUGE amount, 
and you shouldn't ditch that due to not using all features of git :)
To get a grasp of how much that is: When you search projects with more than 
4100 forks, there are only 32 of them!
You are one of the top open source projects, and you should be grateful for 
that and keep Github up so the other people can send you pull requests with 
their improvements :) Volunteer contributions need to be honored and made as 
easy as possible, for people are investing their personal time.

Greetings and thanks for your work,
	xor, one developer of https://freenetproject.org


[1] If you GPG-sign a commit / tag, you sign its hash, including the hash of 
the previous commit. So is a chain of hashes and thus of trust from all 
commits up to what is signed. It's pretty similar to the blockchain actually 
:) 
So Github cannot modify anything. If they did,  the head of the hash-chain 
would change, and thus the signature would break. Git would notify people 
about that when they pull. 
Of course people can still ignore that warning and let Github rewrite their 
Git history. But people who aren't educated about this shouldn't be release 
managers. They should not even have push access to your main repository, they 
should only be sending pull requests. Thats is where the decentralization of 
Git is: In the pull-requests. The people who deal with them should verify tag 
and possibly even commit signatures carefully, and not accept anything which 
is not signed. Also, before deploying a binary, the very same commit which is 
going to become a binary has to be given a signed tag by the release manager, 
and by everyone who reviews the code. The person who deploys the actual binary 
needs to verify that signature.
There is an article which elaborates on some of the ways you have to ensure 
Github doesn't insert malicious code - but please read it with care, some of 
its recommendations are bad, especially the part where its about rebasing 
because that DOES rewrite history which is what you want to prevent:
http://mikegerwitz.com/papers/git-horror-story