stop corruption of .zip files in docs

PR: 25698
Obtained from: Jesse Glick


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@275910 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -957,10 +957,18 @@
     <copy todir="${dist.docs}">
       <fileset dir="${docs.dir}" excludes="${unfiltered.files}">
         <patternset refid="site.excludes"/>
+        <exclude name="**/*.zip"/>
       </fileset>
       <filterchain refid="ant.filters"/>
     </copy>
 
+    <copy todir="${dist.docs}">
+      <fileset dir="${docs.dir}" excludes="${unfiltered.files}">
+        <include name="**/*.zip"/>
+        <patternset refid="site.excludes"/>
+      </fileset>
+    </copy>
+
     <copy todir="${dist.docs}" filtering="false">
       <fileset dir="${docs.dir}" includes="${unfiltered.files}">
         <patternset refid="site.excludes"/>