The claim was that a pull request is not a git concept, I think that's demonstratively false. I won't deny that GitHub popularized it, but they have by no means invented it.

As another piece of evidence, see this page https://www.kernel.org/doc/Documentation/SubmittingPatches

It says Linus (and other kernel maintainer) will want a pull request from you if you want to contribute code, yet he thinks GitHubs version of pull request is, well, lacking (http://www.wired.com/2012/05/torvalds_github/)