$ git clone -n https://src.fedoraproject.org/rpms/ghc-math-functions.git /var/lib/mock/f40-build-2095235-50374/root/chroot_tmpdir/scmroot/ghc-math-functions
Cloning into '/var/lib/mock/f40-build-2095235-50374/root/chroot_tmpdir/scmroot/ghc-math-functions'...
$ git fetch origin e508733a5af86c354c0f57fa344598ec92152bdf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-math-functions
 * [new ref]         e508733a5af86c354c0f57fa344598ec92152bdf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e508733 test fails with QuickCheck 2.14.3