pylint #21870 check some useless "return" [open]

When a function returns nothing and is used as return of another function, pylint could complain something similar to E1111 error:

def alls():
  """all files"""
  print "hello"

def bells():
  """ring ring"""
  aggs = alls() # here we get E1111
  return alls() # here we should also complain...
done in<not specified>
closed by<not specified>