Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/tests/test-524.cs

@@ -0,0 +1,25 @@
+using System;
+
+public class Foo
+{
+	public static int Main ()
+	{
+		try {
+			lock (null) {
+				return 1;
+			}
+		} catch (ArgumentNullException) {
+		}
+
+		for (int i = 0; i < 3; ++i) {
+			object token = new object ();
+
+			lock (token)
+			{
+				token = null;
+			}
+		}
+
+		return 0;
+	}
+}