fix oversight in nodegit#802

Author: maxkorp

generate/scripts/helpers.js

@@ -262,9 +262,11 @@ var Helpers = {
       // itself and determine if this function goes on the prototype
       // or is a constructor method.
       arg.isReturn = arg.name === "out" || (utils.isDoublePointer(arg.type) && normalizedType == typeDef.cType);
-      arg.isSelf = utils.isPointer(arg.type) &&
-        normalizedType == typeDef.cType &&
-        _.every(allArgs, function(_arg) { return !_arg.isSelf; });
+      if (typeof arg.isSelf == 'undefined') {
+        arg.isSelf = utils.isPointer(arg.type) &&
+          normalizedType == typeDef.cType &&
+          _.every(allArgs, function(_arg) { return !_arg.isSelf; });
+      }
 
       if (arg.isReturn && fnDef.return && fnDef.return.type === "int") {
         fnDef.return.isErrorCode = true;