$ git clone -n https://src.fedoraproject.org/rpms/rust-libgit2-sys.git /var/lib/mock/f39-build-1467039-33714/root/chroot_tmpdir/scmroot/rust-libgit2-sys
Cloning into '/var/lib/mock/f39-build-1467039-33714/root/chroot_tmpdir/scmroot/rust-libgit2-sys'...
$ git fetch origin 985d718af2a65f717796c8936bd26e28572187e5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-libgit2-sys
 * [new ref]         985d718af2a65f717796c8936bd26e28572187e5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 985d718 Update to version 0.16.1+1.7.1; Fixes RHBZ#2235484