Methods Element.getchildren(), Element.getiterator() and ElementTree.getiterator() deprecated in 2.7 and 3.2.
Use list(elem) or iteration instead of getchildren(), methods iter() instead of getiterator().
The html argument of XMLParser deprecated in 3.4.
The rest of arguments are keyword-only now (passing them as keywords was recommended in the documentatin).
The support of the doctype() method of XMLParser subclasses and its default implementation. Deprecated in 3.2. Define the doctype() method on a custom TreeBuilder target instead.
The xml.etree.cElementTree module deprecated in 3.3.
Unfortunately some of these deprecations are in the documentation only or in Python implementatation, but not in C implementatation. Perhaps missed warnings should be added first (see bpo-29204). But if commit the patch from bpo-29204 in 3.6, perhaps deprecated features could be removed in 3.7.