https://docs.python.org/3.5/library/array.html describes the 'I' and 'i' typecodes as being minimum-size in bytes of 2. The interpreter disagrees:

>>> import array
>>> a = array.array('i')
>>> a.itemsize
4

There is also a bug with the 'L' and 'l' long typecodes, which document as min-size of 4 bytes but are 8 bytes in the interpreter. That could be a bug in cPython itself though, as if 'L' should be 8 bytes, that disagrees with the type code sizing from the struct module, where it is 4 bytes, just like integers.

I checked documentation for all versions of python and it matches -- I did not check all python interpreters to see they match, but 2.7 and 3.5 did.