If anyone stumbles upon this and gets the following error type:
do not know how to unpack source archive /nix/store/1qiib37qlm1z239mfr5020m4a1ig2abhlnwava7il8dqvrxzsxpl-loc-0.4.0-vendor
You need to set the file type in name:
...
cargoDeps = drv.cargoDeps.overrideAttrs (lib.const {
name = "${name}-vendor.tar.gz";
inherit src;
outputHash = "1qiib37qlm1z239mfr5020m4a1ig2abhlnwava7il8dqvrxzsxpl";
});
...