The OP reported a real mismatch between doc and behavior.  If the
behavior is not changed, I think the doc should be.  Other implementors,
reading the doc, might think that they do have to write code to track
changes.  From the doc, I thought that CPython did that.

So I suggest changing reopening and changing the doc to say
"Changing the net size of the dictionary while using iteritems() will
raise a RuntimeError."  Same for iterkeys() and itervalues()[sp?]

Or remove the warning, as happened in the Py3 changeover to views, or
was that a mistake?