$ git clone -n https://src.fedoraproject.org/rpms/rust-untrusted.git /var/lib/mock/f39-build-1445579-32653/root/chroot_tmpdir/scmroot/rust-untrusted
Cloning into '/var/lib/mock/f39-build-1445579-32653/root/chroot_tmpdir/scmroot/rust-untrusted'...
$ git fetch origin db09e53340037fa95477c93f9a53a7c0fe0bb14d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-untrusted
 * [new ref]         db09e53340037fa95477c93f9a53a7c0fe0bb14d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at db09e53 Update to version 0.9.0; Fixes RHBZ#1956576