proxy needs to add weavewait to execs as well

Bug came up in a test where we are restarting and doing an exec checking
a network interface right away. weavewait is only added if the container
has a WEAVE_CIDR var set, the same as at container creation.

proxy/create_container_interceptor.go

@@ -75,7 +75,7 @@ func (i *createContainerInterceptor) setWeaveWaitEntrypoint(container *docker.Co
 		command = image.Cmd
 	}
 
-	container.Entrypoint = []string{"/home/weavewait/weavewait"}
+	container.Entrypoint = weaveWaitEntrypoint
 	container.Cmd = append(entry, command...)
 	return nil
 }