logilab-astng #37868 relative import problem [validation pending]

pylint 0.21.1, logilab.astng 0.20.1, logilab.common-0.50.3, python 2.7

A model package "p":

$ cat p/__init__.py

$ cat p/a.py
def dummy():
      pass

$ cat p/b.py
from p import a
a.dummy()

$ cat p/c.py
from . import a
a.dummy()

With p/b.py lint work fine:

$ PYTHONPATH=. python27 -m pylint.lint p.b
************* Module p.b
C:  1: Missing docstring

But it fails on p/c.py:

$ PYTHONPATH=. python27 -m pylint.lint p.c
************* Module p.c
C:  1: Missing docstring
Traceback (most recent call last):
File "C:\Python27\Lib\runpy.py", line 162, in _run_module_as_main
  "__main__", fname, loader, pkg_name)
File "C:\Python27\Lib\runpy.py", line 72, in _run_code
  exec code in run_globals
File "C:\Python27\lib\site-packages\pylint\lint.py", line 914, in <module>
  Run(sys.argv[1:])
File "C:\Python27\lib\site-packages\pylint\lint.py", line 856, in __init__
  linter.check(args)
File "C:\Python27\lib\site-packages\pylint\lint.py", line 488, in check
  self.check_astng_module(astng, walker, rawcheckers)
File "C:\Python27\lib\site-packages\pylint\lint.py", line 563, in check_astng_module
  walker.walk(astng)
File "C:\Python27\lib\site-packages\pylint\utils.py", line 516, in walk
  self.walk(child)
File "C:\Python27\lib\site-packages\pylint\utils.py", line 513, in walk
  cb(astng)
File "C:\Python27\lib\site-packages\pylint\checkers\variables.py", line 424, in visit_from
  name_parts = node.modname.split('.')
AttributeError: 'NoneType' object has no attribute 'split'