Earlier today I tried doing a build without substitutes. I was surprised to see this error:
Starting download of /gnu/store/hg3692jqq4jmhg4qx8d7y67fspimy898-?id=3ba68f9e64fa2eb8af22d510437a0c6441feb5e0 >From >http://git.savannah.gnu.org/cgit/coreutils.git/patch/?id=3ba68f9e64fa2eb8af22d510437a0c6441feb5e0... patch 1.2MiB/s 00:00 | 1KiB transferred output path `/gnu/store/hg3692jqq4jmhg4qx8d7y67fspimy898-?id=3ba68f9e64fa2eb8af22d510437a0c6441feb5e0' should have sha256 hash `1dnlszhc8lihhg801i9sz896mlrgfsjfcz62636prb27k5hmixqz', instead has `0zygncr1z1nswmny2vl1havfqswm40vzj0vjvhf5yndavhzr267j' >From the coreutils definition: (patches (list (origin (method url-fetch) (uri "http://git.savannah.gnu.org/cgit/coreutils.git/\ patch/?id=3ba68f9e64fa2eb8af22d510437a0c6441feb5e0") (sha256 (base32 "1dnlszhc8lihhg801i9sz896mlrgfsjfcz62636prb27k5hmixqz")) (file-name "coreutils-tail-inotify-race.patch")))))) But indeed, it's not surprising that there's a hash mismatch... there's nothing here! http://git.savannah.gnu.org/cgit/coreutils.git/patch/?id=3ba68f9e64fa2eb8af22d510437a0c6441feb5e0