$ git clone -n https://src.fedoraproject.org/rpms/python3.7.git /var/lib/mock/f39-build-1620783-38698/root/chroot_tmpdir/scmroot/python3.7
Cloning into '/var/lib/mock/f39-build-1620783-38698/root/chroot_tmpdir/scmroot/python3.7'...
$ git fetch origin b07497fd73f6fcb909281870f6622c6487fe1c5b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python3.7
 * [new ref]         b07497fd73f6fcb909281870f6622c6487fe1c5b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b07497f Remove extra distro-applied CFLAGS passed to user-built C extensions