sympy/sympy — pull request #2181 by jrioux (2013-06-17 16:29:27+00:00)
Title: Fix issue 3890: dsolve failing for an equality multiplied by -1

http://code.google.com/p/sympy/issues/detail?id=3890

One issue was the reordering or args, which should not happen for Tuple instances (e.g. ExprCondPair), and another issue was the unneeded call to piecewise_fold.