fix endline in the signal.py

tests/test_signals.py

@@ -59,16 +59,14 @@ def test_before_render_template():
         context['whiskey'] = 43
         recorded.append((template, context))
 
-    flask.before_render_template.connect(record, app)
-    try:
+    with flask.before_render_template.connected_to(record):
         rv = app.test_client().get('/')
         assert len(recorded) == 1
         template, context = recorded[0]
         assert template.name == 'simple_template.html'
         assert context['whiskey'] == 43
         assert rv.data == b'<h1>43</h1>'
-    finally:
-        flask.before_render_template.disconnect(record, app)
+
 
 def test_request_signals():
     app = flask.Flask(__name__)