$ git clone -n https://src.fedoraproject.org/rpms/rust-sval_buffer.git /var/lib/mock/f39-build-1965566-43292/root/chroot_tmpdir/scmroot/rust-sval_buffer
Cloning into '/var/lib/mock/f39-build-1965566-43292/root/chroot_tmpdir/scmroot/rust-sval_buffer'...
$ git fetch origin 5d9e425a854a02eb29fbe84a004d00fde237c0bd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-sval_buffer
 * [new ref]         5d9e425a854a02eb29fbe84a004d00fde237c0bd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5d9e425 Update to version 2.10.2; Fixes RHBZ#2239965