from import … in __init__.py makes module name visible?

Take the following code example:

File package1/__init__.py:

from moduleB import foo
print moduleB.__name__

File package1/moduleB.py:

def foo(): pass

Then from the current directory:

>>> import package1
package1.moduleB

This code works in CPython. What surprises me about it is that the from ... import in __init__.py statement makes the moduleB name visible. According to Python documentation, this should not be the case:

The from form does not bind the module name

Could someone please explain why CPython works that way? Is there any documentation describing this in detail?