Fix #110, handle 0 beta electrons in uhf_symm
Fix #110, handle 0 beta electrons in uhf_symm

gkc1000/pyscf,gkc1000/pyscf,gkc1000/pyscf,gkc1000/pyscf,gkc1000/pyscf,sunqm/pyscf,sunqm/pyscf,sunqm/pyscf,sunqm/pyscf