While there is no fetcher or builder (in nixpkgs) that takes an `md5` parameter,
for some inscrutable reason the nix interpreter accepts the following:
```nix
fetchurl {
url = "https://www.perdu.com";
hash = "md5-rrdBU2a35b2PM2ZO+n/zGw==";
}
```
Note that neither MD5 nor SHA1 are allowed by the syntax of SRI hashes.