$ git clone -n https://src.fedoraproject.org/rpms/rust-timerfd.git /var/lib/mock/f38-build-side-43-rust-devel-1417003-31458/root/chroot_tmpdir/scmroot/rust-timerfd
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1417003-31458/root/chroot_tmpdir/scmroot/rust-timerfd'...
$ git fetch origin 21d3d7e91166aa8388ab9820f66b2035b7055822:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-timerfd
 * [new ref]         21d3d7e91166aa8388ab9820f66b2035b7055822 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 21d3d7e Update to version 1.5.0; Fixes RHBZ#2213659