$ git clone -n https://src.fedoraproject.org/rpms/rust-untrusted0.7.git /var/lib/mock/f42-build-3251804-41222/root/chroot_tmpdir/scmroot/rust-untrusted0.7
Cloning into '/var/lib/mock/f42-build-3251804-41222/root/chroot_tmpdir/scmroot/rust-untrusted0.7'...
$ git fetch origin 51f14c3787f2867378fb03e6bd69cd95d4d75bf9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-untrusted0.7
 * [new ref]         51f14c3787f2867378fb03e6bd69cd95d4d75bf9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 51f14c3 compat package no longer needed