$ git clone -n https://src.fedoraproject.org/rpms/rust-bstr0.2.git /var/lib/mock/f41-build-side-1-2923647-34982/root/chroot_tmpdir/scmroot/rust-bstr0.2
Cloning into '/var/lib/mock/f41-build-side-1-2923647-34982/root/chroot_tmpdir/scmroot/rust-bstr0.2'...
$ git fetch origin 48a2d4f0af04f6bdc019d70b29804f1305a794e6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-bstr0.2
 * [new ref]         48a2d4f0af04f6bdc019d70b29804f1305a794e6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 48a2d4f compat package no longer needed