use EnvVars to handle case insensitive lookup correctly.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@6313 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/EnvVars.java

@@ -64,7 +64,7 @@ public class EnvVars extends TreeMap<String,String> {
     /**
      * Environmental variables that we've inherited.
      */
-    public static final Map<String,String> masterEnvVars = System.getenv();
+    public static final Map<String,String> masterEnvVars = new EnvVars(System.getenv());
 
     /**
      * Compares strings case insensitively.