Made zip extraction more failsafe.

git-svn-id: http://svn.igniterealtime.org/svn/repos/messenger/trunk@2671 b35dd754-fafc-0310-a699-88a17e54d16e

build/build.xml

@@ -586,7 +586,8 @@
             <fileset dir="${webapp.dest.dir}"/>
         </copy>
         <!-- Copy help files -->
-        <unzip src="${src.dir}/help/help.zip" dest="${prepare.out.dir}/plugins/admin/webapp" />
+        <available file="${src.dir}/help/help.zip" property="help.exists" />
+        <antcall target="-extract-help" />
         <!-- Copy in tag library support -->
         <copy todir="${prepare.out.dir}/lib">
             <fileset dir="${lib.build.dir}" includes="commons-el.jar"/>
@@ -603,6 +604,10 @@
 
     </target>
 
+    <target name="-extract-help" if="help.exists">
+        <unzip src="${src.dir}/help/help.zip" dest="${prepare.out.dir}/plugins/admin/webapp" />
+    </target>
+
     <!-- release =============================================================================== -->
     <target name="release" depends="jar,javadoc" description="Creates a distribution">
         <mkdir dir="${release.dest.dir}"/>