@itsmeholland @astraleureka
It's not that it took long to discover, it's that it took an incredibly lucky coincidence, and a mistake on the attacker's part.
There could be 50 more backdoors like this that we don't know about and there's no reason for them to be caught.
Part of the problem is that some parts of open-source software (eg. build scripts) are often hard to audit despite being open-source (this is fixable).
Another part is insufficient amount of people wants to audit software.