remove checking of node.docstring (#704)

this was only present during a brief period of 3.7 pre-release

Author: asottile

pyflakes/checker.py

@@ -1439,19 +1439,7 @@ def handleNode(self, node, parent):
 
     def handleDoctests(self, node):
         try:
-            if hasattr(node, 'docstring'):
-                docstring = node.docstring
-
-                # This is just a reasonable guess. In Python 3.7, docstrings no
-                # longer have line numbers associated with them. This will be
-                # incorrect if there are empty lines between the beginning
-                # of the function and the docstring.
-                node_lineno = node.lineno
-                if hasattr(node, 'args'):
-                    node_lineno = max([node_lineno] +
-                                      [arg.lineno for arg in node.args.args])
-            else:
-                (docstring, node_lineno) = self.getDocstring(node.body[0])
+            (docstring, node_lineno) = self.getDocstring(node.body[0])
             examples = docstring and self._getDoctestExamples(docstring)
         except (ValueError, IndexError):
             # e.g. line 6 of the docstring for <string> has inconsistent