There is a reference leak when using PyType_FromSpec with custom tp_dealloc.  This was first noted in issue #15142, where a fix was given which only applies to types which do not override tp_dealloc.

For example, the xxlimited.Xxo type suffers from this:

Python 3.3.0 (default, Oct 26 2012, 11:06:17) 
[GCC 4.6.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import xxlimited
>>> import sys
>>> Xxo = type(xxlimited.new())
>>> e = Xxo()
>>> sys.getrefcount(Xxo)
7
>>> e = Xxo()
>>> sys.getrefcount(Xxo)
8
>>> e = Xxo()
>>> sys.getrefcount(Xxo)
9