$ git clone -n https://src.fedoraproject.org/rpms/perl-Thread-SigMask.git /var/lib/mock/f41-build-817029-150576/root/chroot_tmpdir/scmroot/perl-Thread-SigMask
Cloning into '/var/lib/mock/f41-build-817029-150576/root/chroot_tmpdir/scmroot/perl-Thread-SigMask'...
$ git fetch origin 931e928beefbcd4403d640bda55726a32e475c52:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Thread-SigMask
 * [new ref]         931e928beefbcd4403d640bda55726a32e475c52 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 931e928 Perl 5.40 rebuild