Close client connection once 'ready' message arrives

In our tests when we pretend to be a web browser we were waiting for
BinderHub to close the network connection while streaming the response.
Because BinderHub waits "a long time" after sending the "ready" message
this was slowing down the tests, as they sat around twiddling their
thumbs.

Author: betatim

binderhub/tests/test_build.py

@@ -52,6 +52,13 @@ async def test_build(app, needs_build, needs_launch, always_build, slug, pytestc
             events.append(event)
             assert 'message' in event
             sys.stdout.write(event['message'])
+            # this is the signal that everything is ready, pod is launched
+            # and server is up inside the pod. Break out of the loop now
+            # because BinderHub keeps the connection open for many seconds
+            # after to avoid "reconnects" from slow clients
+            if event.get('phase') == 'ready':
+                r.close()
+                break
 
     final = events[-1]
     assert 'phase' in final