$ git clone -n https://src.fedoraproject.org/rpms/kdebase3.git /var/lib/mock/f40-build-788721-135313/root/chroot_tmpdir/scmroot/kdebase3
Cloning into '/var/lib/mock/f40-build-788721-135313/root/chroot_tmpdir/scmroot/kdebase3'...
$ git fetch origin 77bfed759f4e68a94aae9153f8b94e0df7735955:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kdebase3
 * [new ref]         77bfed759f4e68a94aae9153f8b94e0df7735955 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 77bfed7 fixed bz#2261271, FTBFS