[mzltest]

They are not testing their skills. Based on OP, they're doing research about insecurities in open source community where all can contribute to an open source repository. Therefore they test the community by releasing questionable commit.

 
But this kind of research is nonsense,since there are various people and no control groups,etc.And they could simply starting a new project with code issues and asking for a peer review,not by harming a existing project,as people basically have a good faith of kindness and they won't actually review every piece of code modified.