python module name contains '.'？

sh$ mv bin.py bin.test.py
sh$ python
Python 2.3.4 (#1, Feb  6 2006, 10:38:46)
[GCC 3.4.5 20051201 (Red Hat 3.4.5-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import bin.test
Traceback (most recent call last):
  File "", line 1, in ?
ImportError: No module named test
>>> import bin
>>> dir(bin)
['__builtins__', '__doc__', '__file__', '__name__', 'dbin', 'dbin8', 'rdbin']
>>>

".test.py" 都被忽略掉了！因为 bin.test.py 会导致查找文件 bin/test.py，当然是不存在的！