$ git clone -n https://src.fedoraproject.org/rpms/ghc-regex-posix.git /var/lib/mock/f45-build-10671-419/root/chroot_tmpdir/scmroot/ghc-regex-posix
Cloning into '/var/lib/mock/f45-build-10671-419/root/chroot_tmpdir/scmroot/ghc-regex-posix'...
$ git fetch origin 8397e9d14887b8565f6a8f749ef24f69fb606bb9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-regex-posix
 * [new ref]         8397e9d14887b8565f6a8f749ef24f69fb606bb9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8397e9d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild