Fix bug updating WeakKeyDictionary during iteration#1698

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efiring merged 1 commit intomatplotlib:v1.2.xfrom

mdboom:iteritems_bug

Feb 17, 2013

Commits on Jan 23, 2013

Fix itervalues -> values. As reported by Massimiliano Costacurta in mailing list thread "BUG: RuntimeError: dictionary changed size during iteration"
mdboom
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