There is nothing to be gained from using cryptographic primitives in a non-security context. You could just as easily use e.g. CRC32 for the case you're describing.
There is, however, a performance cost in using cryptographic primitives in non-security-related contexts. You may not care about performance, but it certainly matters for something like git.
Linus claims: "So in git, the hash is used for de-duplication and error detection, and the 'cryptographic' nature is mainly because a cryptographic hash is really good at those things."
CRC produces a distribution just as uniform as a cryptographic hash function, and it's faster to boot. If these are the only things he actually cares about, and he's explicitly discounting security, he's choosing a slower primitive for no reason.
He writes off CRC inexplicably earlier in the post:
"Other SCM's have used things like CRC's for error detection, although honestly the most common error handling method in most SCM's tends to be 'tough luck, maybe your data is there, maybe it isn't, I don't care'."
Linus seems to think that SHA1 has some sort of magic crypto sauce which magically makes the distribution it produces more uniform than CRC's. It doesn't. The only difference is SHA1 was originally designed to be resistant to preimage and collision attacks, both of which are irrelevant outside of a security context.
There is, however, a performance cost in using cryptographic primitives in non-security-related contexts. You may not care about performance, but it certainly matters for something like git.
Linus claims: "So in git, the hash is used for de-duplication and error detection, and the 'cryptographic' nature is mainly because a cryptographic hash is really good at those things."
CRC produces a distribution just as uniform as a cryptographic hash function, and it's faster to boot. If these are the only things he actually cares about, and he's explicitly discounting security, he's choosing a slower primitive for no reason.
He writes off CRC inexplicably earlier in the post:
"Other SCM's have used things like CRC's for error detection, although honestly the most common error handling method in most SCM's tends to be 'tough luck, maybe your data is there, maybe it isn't, I don't care'."
Linus seems to think that SHA1 has some sort of magic crypto sauce which magically makes the distribution it produces more uniform than CRC's. It doesn't. The only difference is SHA1 was originally designed to be resistant to preimage and collision attacks, both of which are irrelevant outside of a security context.