TST Fix AttributeError: 'iterator' object has no attribute 'next' on Python 3
Merge pull request #7148 from cgohlke/patch-1

TST Fix AttributeError: 'iterator' object has no attribute 'next' on Python 3
TST:  test fixes for plotting with old scipy (GH7151)
COMPAT: 2.6 format spec compat

BUG: TestCase instances cant assertRaisesRegexp so use tm
Merge pull request #7153 from cpcloud/test-compat-2.6-7152

BUG/COMPAT: test compat on Python 2.6
BUG: tzinfo lost when concatenating multiindex arrays