RUBY-206 handle wtimeout behavior on 1.7.3

lib/mongo/connection.rb

@@ -387,6 +387,7 @@ module Mongo
 
       if num_received == 1 && (error = docs[0]['err'] || docs[0]['errmsg'])
         close if error == "not master"
+        error = "wtimeout" if error == "timeout"
         raise Mongo::OperationFailure, docs[0]['code'].to_s + ': ' + error
       end
 

lib/mongo/db.rb

@@ -468,8 +468,12 @@ module Mongo
         raise MongoArgumentError, "DB#command requires an OrderedHash when hash contains multiple keys"
       end
 
-      result = Cursor.new(system_command_collection,
-        :limit => -1, :selector => selector, :socket => sock).next_document
+      begin
+        result = Cursor.new(system_command_collection,
+          :limit => -1, :selector => selector, :socket => sock).next_document
+      rescue OperationFailure => ex
+        raise OperationFailure, "Database command '#{selector.keys.first}' failed: #{ex.message}"
+      end
 
       if result.nil?
         raise OperationFailure, "Database command '#{selector.keys.first}' failed: returned null."