War of the wallpaper! I think my fix to remove bogus extra dynscope p…

…er simple eval

exposed that we somewhere pop off toplevel scope before the runtime shuts down.  To
counteract this I add back a bogus scope only for shutdown.  This is likely a bug
in that any capture lvars in at_exit blocks is likely lost (haven't tested), but
this makes mspec fast run without error for now.

core/src/main/java/org/jruby/Ruby.java

@@ -42,6 +42,7 @@
 import org.jruby.compiler.Constantizable;
 import org.jruby.compiler.NotCompilableException;
 import org.jruby.ir.IRScriptBody;
+import org.jruby.parser.StaticScope;
 import org.objectweb.asm.util.TraceClassVisitor;
 
 import jnr.constants.Constant;
@@ -3164,6 +3165,16 @@ public void tearDown(boolean systemExit) {
         // clear out threadlocals so they don't leak
         recursive = new ThreadLocal<Map<String, RubyHash>>();
 
+        ThreadContext context = getCurrentContext();
+
+        // FIXME: 73df3d230b9d92c7237d581c6366df1b92ad9b2b exposed no toplevel scope existing anymore (I think the
+        // bogus scope I removed was playing surrogate toplevel scope and wallpapering this bug).  For now, add a
+        // bogus scope back for at_exit block run.  This is buggy if at_exit is capturing vars.
+        if (!context.hasAnyScopes()) {
+            StaticScope topStaticScope = getStaticScopeFactory().newLocalScope(null);
+            context.pushScope(new ManyVarsDynamicScope(topStaticScope, null));
+        }
+
         while (!atExitBlocks.empty()) {
             RubyProc proc = atExitBlocks.pop();
             try {

core/src/main/java/org/jruby/runtime/ThreadContext.java

@@ -533,6 +533,10 @@ public static void popBacktrace(ThreadContext context) {
         context.backtraceIndex--;
     }
 
+    public boolean hasAnyScopes() {
+        return scopeIndex > -1;
+    }
+
     /**
      * Check if a static scope is present on the call stack.
      * This is the IR equivalent of isJumpTargetAlive