[Terry N.] force overwrite

examples/build.xml

@@ -216,12 +216,12 @@ POSSIBILITY OF SUCH DAMAGE.
     </target>
 
     <target name="-post-jar" description="compiles all classes into a single utility jar for MV3500 course use of viskit">
-        <copy todir="${viskit.proj.lib.dir}">
+        <copy todir="${viskit.proj.lib.dir}" overwrite="true">
             <fileset dir="${dist.dir}">
                 <include name="${dist.name}.jar"/>
             </fileset>
         </copy>
-        <copy todir="${2024.cohort.assign.viskit.ex.proj.lib.dir}">
+        <copy todir="${2024.cohort.assign.viskit.ex.proj.lib.dir}" overwrite="true">
             <fileset dir="${dist.dir}">
                 <include name="${dist.name}.jar"/>
             </fileset>