From PEP 411:

"""
A package will be marked provisional by a notice in its documentation page and its docstring. The following paragraph will be added as a note at the top of the documentation page:

    The <X> package has been included in the standard library on a provisional basis. Backwards incompatible changes (up to and including removal of the package) may occur if deemed necessary by the core developers.
"""

PEP 3156 says that asyncio is in provisional status until Python 3.5, but the main asyncio page in the docs does not even mention this, let alone having the new warning:
https://docs.python.org/3/library/asyncio.html

I freely admit this is nitpicking, but if the idea of provisional status is to be taken seriously, I think asyncio, as a very high profile new package, should set a good example of it.

New changeset f8f3e83c9528 by Guido van Rossum in branch 'default':
Add PEP-411-compliant note about asyncio being provisional. Fixes issue #22346.
http://hg.python.org/cpython/rev/f8f3e83c9528

Thanks!

New changeset fefe7822e6b8 by Nick Coghlan in branch '3.4':
Issue #22346: also include asyncio PEP 411 notice in 3.4
http://hg.python.org/cpython/rev/fefe7822e6b8