I feel like this still ignores most of what Linus said on why git isn't broken. In particular "it's fairly trivial to detect the fingerprints of using this attack" in his Google+ post. https://plus.google.com/+LinusTorvalds/posts/7tp2gYWQugL
And there are already patches on the mailing list for that.
I think the fingerprint argument is pretty weak actually. There is still a lot of unreadable content in git repos, including binary blobs in the kernel.
He doesn't mean manually recognising the fingerprint
Correct. He's talking about the automated method used on shattered.io to detect files which use the attack. See: https://github.com/cr-marcstevens/sha1collisiondetection
They're basically building that into git so that if this specific collision attack is ever used, git will notice and throw a warning/error.