collections.abc was renamed _collections_abc in issue 19218.  The __init__ file was modified to load all the abc into the collections namespace, but the 'abc' name itself is no longer defined:

Python 3.3.2 (default, Dec 17 2013, 17:24:42) 
[GCC 4.7.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import collections
>>> collections.abc
<module 'collections.abc' from '/usr/lib/python3.3/collections/abc.py'>

Python 3.4.0rc1+ (default:1bc585ba5df2, Feb 24 2014, 15:04:31) 
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import collections
>>> collections.abc
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'abc'

It looks like the import statement for _collections_abc in the __init__ file as has missing "as abc" phrase.

This is probably not important enough to require fixing in the RC, since 'import collections.abc' works fine, but it is a regression.