sympy/sympy — pull request #904 by flacjacket (2011-12-29 03:20:37+00:00)
Title: Improve handling of qapply'ing symbolic spin states with basis conversion

This takes care of some previously XFAIL tests using qapply to evaluate a spin operator with a symbolic state that requires a sum over Wigner-D functions to evaluate. This defines a method which deals with spin operators applied to sums. It also checks that the _apply_op method is doing something before returning it.