sympy/sympy — pull request #1217 by Botouls (2012-04-06 14:23:19+00:00)
Title: Fix to issue 3206 - Abs should denest

This should fix the problem when Abs() is called with another Abs() as parameter
If you enter Abs(Abs(x)) it would return Abs(Abs(x)). With the fix Abs(Abs(x)) will return Abs(x)