$ git clone -n https://src.fedoraproject.org/rpms/rust-darling0.14.git /var/lib/mock/f40-build-2115355-50685/root/chroot_tmpdir/scmroot/rust-darling0.14
Cloning into '/var/lib/mock/f40-build-2115355-50685/root/chroot_tmpdir/scmroot/rust-darling0.14'...
$ git fetch origin b1d5007b2940f4842708ba93a5a92e2b441f5243:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-darling0.14
 * [new ref]         b1d5007b2940f4842708ba93a5a92e2b441f5243 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b1d5007 Initial import (darling 0.14 compat package)