$ git clone -n https://github.com/xcp-ng-rpms/libssh2 /var/lib/mock/v8.3-incoming-10662-29215/root/chroot_tmpdir/scmroot/libssh2
Cloning into '/var/lib/mock/v8.3-incoming-10662-29215/root/chroot_tmpdir/scmroot/libssh2'...
$ git fetch origin 7dfe4694250535059cbe734188ad72c0cb80a720:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libssh2
 * [new ref]         7dfe4694250535059cbe734188ad72c0cb80a720 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7dfe469 Merge pull request #1 from xcp-ng-rpms/8.3-XS-1557