If you do a write to the config database through mongos in 2.4 and the shell is in verbose mode, the shell prints a "norepl" error message.

> set verbose true
set verbose to true
> use config;
> db.settings.update({_id:'balancer'},{$set:{stopped:true}});
norepl
> 

We shouldn't use w:1 here, we should instead just not specify w at all. Alternatively, we could make GLE on config servers not return "norepl" when given a "w" field if the value of the "w" field is 1.