demandimport: patch __builtin__ instead of __builtins__
This helps on implementations other than CPython, where __builtins__ isn't
necessarily defined (as it's an implementation detail for CPython).
adding a
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
a renamed from b:9a263dd772e0159ddfa70fb8a448bb6c7ec8c69f
% test with --rev
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3