Python import weirdness

gistfile1.txt

(venv)jack@neptune-vm:~/z/imports$ python
Python 2.7.12 (default, Nov 20 2017, 18:23:56) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from a import foo
>>> foo
<module 'a.foo' from 'a/foo.py'>
>>> foo.MY_THING
'THIS IS A STRING DEFINED IN THE MODULE'
>>> exit()
(venv)jack@neptune-vm:~/z/imports$ python
Python 2.7.12 (default, Nov 20 2017, 18:23:56) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from b import foo
>>> foo
'THIS IS A STRING DEFINIED IN __init__.py'
>>> exit()
(venv)jack@neptune-vm:~/z/imports$ python
Python 2.7.12 (default, Nov 20 2017, 18:23:56) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from c import foo
>>> foo
'THIS IS A STRING DEFINIED IN __init__.py'
>>> c.foo
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'c' is not defined
>>> import c
>>> c.foo
'THIS IS A STRING DEFINIED IN __init__.py'
>>> from c.foo import MY_THING
>>> MY_THING
'THIS IS A STRING DEFINED IN THE MODULE'
>>> import c.foo
>>> c.foo
<module 'c.foo' from 'c/foo.py'>