add a delay so new zip is certain to get a more recent timestamp

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@794527 13f79535-47bb-0310-9956-ffa450edef68

src/tests/antunit/taskdefs/zip-test.xml

@@ -115,6 +115,7 @@
       <copy file="${output}/jar.jar" tofile="${output}/reference.jar"/>
 
       <mkdir dir="${input}/y"/>
+      <sleep seconds="2"/>
       <jar jarfile="${output}/jar.jar">
         <fileset dir="${input}"/>
       </jar>