As mentioned elsewhere in this discussion AdBlock is not Adblock Plus. The second link you posted is for the Adblock Plus source code.
Unfortunately at the moment the AdBlock Git repository is not public, but I have set up this unofficial one that tracks the changes between each zip published on their releases page. https://github.com/kzar/watchadblock
Nice, this makes it much easier to track changes. For those interested, here is a URL which can be used as a template to diff across releases:
https://github.com/kzar/watchadblock/compare/[old version]...[new version]
For example, for all the changes between releases 2.40 and 2.41.1:
https://github.com/kzar/watchadblock/compare/2.40...2.41.1