nodeadmin: node stops itself if a hotline file hasn't been touched in 120 seconds now, instead of in 60 seconds

A test failed on draco (MacPPC) because it took 67.1 seconds to get around to running the test, and the node had already stopped itself when the hotline file was 60 seconds old.

src/allmydata/client.py

@@ -300,7 +300,7 @@ class Client(node.Node, pollmixin.PollMixin):
     def _check_hotline(self, hotline_file):
         if os.path.exists(hotline_file):
             mtime = os.stat(hotline_file)[stat.ST_MTIME]
-            if mtime > time.time() - 60.0:
+            if mtime > time.time() - 120.0:
                 return
             else:
                 self.log("hotline file too old, shutting down")