[Nix-dev] Why does fetchgit not look at the URL to determine the cache location?

[Rico Huijbers]

Hi,

When I copy/paste a fetchgit block from another file, and change the URL and rev without changing the hash, I expect the download to fail (and tell me the hash).

However, what actually happens is that fetchgit just looks at the hash, sees that *something* with that hash has already been downloaded, and happily proceeds with the rest of the script using the wrong source files. Now I have to go and do nix-prefetch-git every time. 

Shouldn’t fetchgit build the hash from URL and rev, as opposed to the provided hash? Or am I doing it wrong?

Regards,
Rico