tests are on system classpath of forked tests

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276898 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -534,6 +534,7 @@
         <!-- absolute paths in CLASSPATH -->
         <contains string="${java.class.path}"
                   substring="${build.tests.resolved}"/>
+        <istrue value="${junit.fork}"/>
       </or>
     </condition>