sympy/sympy — pull request #1675 by jrioux (2012-11-26 12:24:54+00:00)
Title: Fix simplify issue 3476

Don't call cancel on noncommutative expr.

Fixes issue 3476: simplify and noncommutative symbol error
http://code.google.com/p/sympy/issues/detail?id=3476

>>> from sympy import Symbol, symbols, simplify
>>> A = Symbol("A", commutative=False)
>>> x, y = symbols("x y")
>>> simplify(A/(1 + y/x))
x*A/(x + y)