$ git clone -n https://src.fedoraproject.org/rpms/ghc-HsYAML.git /var/lib/mock/f40-build-743570-111265/root/chroot_tmpdir/scmroot/ghc-HsYAML
Cloning into '/var/lib/mock/f40-build-743570-111265/root/chroot_tmpdir/scmroot/ghc-HsYAML'...
$ git fetch origin f74142a4f00f8f2a8f5ee7815b2f7fe8962962dc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-HsYAML
 * [new ref]         f74142a4f00f8f2a8f5ee7815b2f7fe8962962dc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f74142a revised .cabal file