$ git clone -n https://src.fedoraproject.org/rpms/relaxng-datatype-java.git /var/lib/mock/f42-build-3384212-45084/root/chroot_tmpdir/scmroot/relaxng-datatype-java
Cloning into '/var/lib/mock/f42-build-3384212-45084/root/chroot_tmpdir/scmroot/relaxng-datatype-java'...
$ git fetch origin f5519c54ffe42358a1e2c19d21cef093b7752d29:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/relaxng-datatype-java
 * [new ref]         f5519c54ffe42358a1e2c19d21cef093b7752d29 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f5519c5 Remove javadoc subpackage