Close connection before attaching on 'up' and 'run'

This ensures that the connection is not recycled, which can cause the
Docker daemon to complain if we've already performed another streaming
call such as doing a build.

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

compose/service.py

@@ -476,6 +476,11 @@ class Service(object):
         except StreamOutputError as e:
             raise BuildError(self, unicode(e))
 
+        # Ensure the HTTP connection is not reused for another
+        # streaming command, as the Docker daemon can sometimes
+        # complain about it
+        self.client.close()
+
         image_id = None
 
         for event in all_events: