Do not check state on other threads in autoload spec

* It's unclear if the MRI semantics are correct,
  see https://bugs.ruby-lang.org/issues/15663
* The constant should logically remain defined on other threads while
  it is loading.

Author: eregon

spec/ruby/core/module/autoload_spec.rb

@@ -260,7 +260,7 @@ module ModuleSpecs::Autoload
       nested_require = -> {
         result = nil
         ScratchPad.record -> {
-          result = [@check.call, Thread.new { @check.call }.value]
+          result = @check.call
         }
         require nested
         result
@@ -269,9 +269,7 @@ module ModuleSpecs::Autoload
 
       @check.call.should == ["constant", @path]
       require @path
-      cur, other = ScratchPad.recorded
-      cur.should == [nil, nil]
-      other.should == [nil, nil]
+      ScratchPad.recorded.should == [nil, nil]
       @check.call.should == ["constant", nil]
     end
   end