$ git clone -n https://src.fedoraproject.org/rpms/jakarta-mail1.git /var/lib/mock/f40-build-2546648-61909/root/chroot_tmpdir/scmroot/jakarta-mail1
Cloning into '/var/lib/mock/f40-build-2546648-61909/root/chroot_tmpdir/scmroot/jakarta-mail1'...
$ git fetch origin 5525c58e0619b22f7c309c4c51acbf2547f66010:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jakarta-mail1
 * [new ref]         5525c58e0619b22f7c309c4c51acbf2547f66010 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5525c58 Java version 7 no longer supported - use version 8