[Truffle] Don't remove an autoloaded constant on failure.

Author: nirvdrum

spec/truffle/tags/core/module/autoload_tags.txt

@@ -2,7 +2,6 @@ fails:Module#autoload loads the registered constant when it is opened as a class
 fails:Module#autoload loads the registered constant when it is opened as a module
 fails:Module#autoload does not load the file if the file is manually required
 fails:Module#autoload ignores the autoload request if the file is already loaded
-fails:Module#autoload does not remove the constant from the constant table if load fails
 fails:Module#autoload does not remove the constant from the constant table if the loaded files does not define it
 fails:Module#autoload loads the file when opening a module that is the autoloaded constant
 fails:Module#autoload looks up the constant when in a meta class scope

truffle/src/main/java/org/jruby/truffle/nodes/dispatch/UnresolvedDispatchNode.java

@@ -207,8 +207,6 @@ private Object doRubyBasicObject(
                     requireNode = insert(KernelNodesFactory.RequireNodeFactory.create(getContext(), getSourceSection(), new RubyNode[]{}));
                 }
 
-                module.removeConstant(this, (String) methodName);
-
                 requireNode.require((RubyString) constant.getValue());
 
                 return doRubyBasicObject(frame, first, receiverObject, methodName, blockObject, argumentsObjects);

truffle/src/main/java/org/jruby/truffle/runtime/core/RubyModule.java

@@ -211,6 +211,7 @@ private void setConstantInternal(RubyNode currentNode, String name, Object value
             getConstants().put(name, new RubyConstant(this, value, false, autoload));
         } else {
             // TODO(CS): warn when redefining a constant
+            // TODO (nirvdrum 18-Feb-15): But don't warn when redefining an autoloaded constant.
             getConstants().put(name, new RubyConstant(this, value, previous.isPrivate(), autoload));
         }