Removing return value of restart_kernel.

The kernel_id is *always* the same under a restart and there
is no need to return it. The restart handler does pass
the original kernel_id back to the browser as it currently uses it.

IPython/frontend/html/notebook/handlers.py

@@ -364,9 +364,9 @@ class KernelActionHandler(AuthenticatedHandler):
             km.interrupt_kernel(kernel_id)
             self.set_status(204)
         if action == 'restart':
-            new_kernel_id = km.restart_kernel(kernel_id)
-            data = {'ws_url':self.ws_url,'kernel_id':new_kernel_id}
-            self.set_header('Location', '/'+new_kernel_id)
+            km.restart_kernel(kernel_id)
+            data = {'ws_url':self.ws_url, 'kernel_id':kernel_id}
+            self.set_header('Location', '/'+kernel_id)
             self.write(jsonapi.dumps(data))
         self.finish()
 

IPython/frontend/html/notebook/kernelmanager.py

@@ -350,7 +350,6 @@ class MappingKernelManager(MultiKernelManager):
         self._check_kernel_id(kernel_id)
         super(MappingKernelManager, self).restart_kernel(kernel_id)
         self.log.info("Kernel restarted: %s" % kernel_id)
-        return kernel_id
 
     def create_iopub_stream(self, kernel_id):
         """Create a new iopub stream."""