[Python-Dev] %x formatting of floats - behaviour change since 3.4

[Chris Angelico]

I'm helping out with the micropython project and am finding that one
of their tests fails on CPython 3.5 (fresh build from Mercurial this
morning). It comes down to this:

Python 3.4.1rc1 (default, May  5 2014, 14:28:34)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> "%x"%16.0
'10'

Python 3.5.0a0 (default:88814d1f8c32, Jun  4 2014, 07:29:32)
[GCC 4.7.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> "%x"%16.0
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: %x format: an integer is required, not float

Is this an intentional change? And if so, is it formally documented
somewhere? I don't recall seeing anything about it, but my
recollection doesn't mean much.

ChrisA