Reproduction:

# main.py
import foo.bar

# foo/__init__.py
# (empty)

# foo/bar/__init__.py
import foo.bar.bing as bing

# foo/bar/bing.py
# (empty)

Result:

dustin@euclid ~/tmp $ python3.3 main.py 
Traceback (most recent call last):
  File "main.py", line 1, in <module>
    import foo.bar
  File "/home/dustin/tmp/foo/bar/__init__.py", line 1, in <module>
    import foo.bar.bing as bing
AttributeError: 'module' object has no attribute 'bar'

dustin@euclid ~/tmp $ python2.7 main.py 
Traceback (most recent call last):
  File "main.py", line 1, in <module>
    import foo.bar
  File "/home/dustin/tmp/foo/bar/__init__.py", line 1, in <module>
    import foo.bar.bing as bing
AttributeError: 'module' object has no attribute 'bar'

If you remove the `as bing` from `foo/bar/__init__.py`, all is well.  Similarly, `from foo.bar import bing` works fine, as does `from foo.bar import bing as bing`.

I don't see anything in https://docs.python.org/3/reference/simple_stmts.html#import that suggests this is expected behavior.