Some progress in 8.8.b2:

less than 1 : 34
less than 2 : 54
less than 4 : 77
less than 8 : 86
less than 16 : 91
less than 64 : 94

In the 15 worst files, 163 broken doctests:

['src/sage/tests/books/computational-mathematics-with-sagemath/graphtheory_doctest.py # 5 doctests failed',
'src/sage/ext/fast_callable.pyx # 6 doctests failed',
'src/sage/groups/perm_gps/permgroup.py # 6 doctests failed',
'src/sage/rings/polynomial/multi_polynomial.pyx # 6 doctests failed',
'src/sage/combinat/root_system/weyl_group.py # 7 doctests failed',
'src/sage/graphs/generic_graph.py # 8 doctests failed',
'src/sage/libs/ntl/ntl_ZZ_pX.pyx # 8 doctests failed',
'src/sage/misc/nested_class.pyx # 9 doctests failed',
'src/sage/rings/integer.pyx # 9 doctests failed',
'src/sage/symbolic/expression.pyx # 12 doctests failed',
'src/sage/combinat/cluster_algebra_quiver/cluster_seed.py # 13 doctests failed',
'src/sage/combinat/cluster_algebra_quiver/quiver.py # 13 doctests failed',
'src/sage/matroids/matroid.pyx # 19 doctests failed',
'src/sage/misc/classcall_metaclass.pyx # 20 doctests failed',
'src/sage/combinat/finite_state_machine.py # 22 doctests failed']