sympy/sympy — pull request #1671 by smichr (2012-11-24 05:47:25+00:00)
Title: iterables fixes, edits and coverage

o fixed some issues with multiset_*
Added a size option to multiset_permutations so it behaves
like the normal permutations (in terms of accepting the option
size arguement)

o rotate_* doesn't return self if self is [] (this is important
since the rotation does not happen in place when there are elements
to rotate

o minlex defaults to is_set=False which is safer; if someone knows
they are working with unique elements they can set is_set to True.

o add multiset convenience function to convert unordered list to
multiset form