$ git clone -n https://src.fedoraproject.org/rpms/gdb.git /var/lib/mock/f40-build-1463650-23590/root/chroot_tmpdir/scmroot/gdb
Cloning into '/var/lib/mock/f40-build-1463650-23590/root/chroot_tmpdir/scmroot/gdb'...
$ git fetch origin efacd9b5f3a542131bf626eec2e33ef87c3ae5a4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gdb
 * [new ref]         efacd9b5f3a542131bf626eec2e33ef87c3ae5a4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at efacd9b Backport upstream commit 91874afabcd to fix RHEL2295897