Don't create a new resource with allow_head=True (#2585)

* Don't create a new resource with allow_head=True

* Add missing changes

CHANGES/2585.removal

@@ -0,0 +1 @@
+Do not create a new resource on `router.add_get(..., allow_head=True)`

aiohttp/web_urldispatcher.py

@@ -879,14 +879,10 @@ def add_get(self, path, handler, *, name=None, allow_head=True, **kwargs):
         Shortcut for add_route with method GET, if allow_head is true another
         route is added allowing head requests to the same endpoint
         """
+        resource = self.add_resource(path, name=name)
         if allow_head:
-            # it name is not None append -head to avoid it conflicting with
-            # the GET route below
-            head_name = name and '{}-head'.format(name)
-            self.add_route(hdrs.METH_HEAD, path, handler,
-                           name=head_name, **kwargs)
-        return self.add_route(hdrs.METH_GET, path, handler, name=name,
-                              **kwargs)
+            resource.add_route(hdrs.METH_HEAD, handler, **kwargs)
+        return resource.add_route(hdrs.METH_GET, handler, **kwargs)
 
     def add_post(self, path, handler, **kwargs):
         """