The source code is over there (GPL): https://hg.adblockplus.org/adblockplus/
The article seems to say this is related to the typo feature, but https://hg.adblockplus.org/adblockplus/file/tip/defaults/typ... has never changed since the introduction of the feature in 2012-11.
"domainReferrals":{"amazon.co.uk":"tag=uf07d-21","amazon.com":"tag=uf024-20","amazon.de":"tag=uf0e6-21","amazon.es":"tag=uf07-21","amazon.fr":"tag=uf02b-21","amazon.it":"tag=uf08d-21","ozon.ru":"partner=urlfixer"},
ABP notifies me of the redirection, and I can accept or blacklist it.
However it appears to add that tag only if I typo the name, if I follow a good Amazon link (with or without the affiliate) then it doesn't get 'corrected'.
Although since the rewrite rules are downloaded from a remote location (over HTTP, not even HTTPS!) they could in theory decide to rewrite any links in the future, without many people noticing.
Edit: sorry about that last part. http://amazon.co does exist and does get corrected.