ipython/ipython — pull request #2311 by minrk (2012-08-16 21:20:55+00:00)
Title: always perform requested trait assignments

Some assignments do not change *value*, but do change the object,
and these should not be ignored.

For instance, container objects are currently impossible to assign
if they evaluate as equal, even if their types don't match
(e.g. assigning an empty defaultdict to a Dict trait)