java Inherit classpath. add vm option "-Dbuild.sysclasspath=last".

build.xml

<macrodef name="single-task">
  <attribute name="application.name" default="AntTask" />
  <attribute name="vm.dir"/>
  <attribute name="build.file"/>
  <element name="build.tasks" />
  <sequential>
    <echo message="start @{application.name}."/>
    
    <!-- デバッグ情報の出力 -->
    <property name="ant-class-path" refid="ant.class.path" />
    <echo message="classpath = ${ant-class-path}" />
    <echo message="tomcat.home = ${tomcat.home}" />
    
    <!-- javaタスクで、build.xmlを実行 -->
    <java classname="org.apache.tools.ant.launch.Launcher" fork="true" dir="@{vm.dir}" failonerror="true">
      <sysproperty key="ant.home" value="${ant.home}"/>
      <arg value="-buildfile" />
      <arg value="@{build.file}" />
      <build.tasks />
      <env key="TOMCAT_HOME" value="${tomcat.home}" />
      <!-- <java cloneVm="true" /> cloneVmは、"-buildfile"オプションが無効になる -->
      <classpath refid="ant.class.path"/>
    </java>
    <echo message="complete @{application.name}."/>
  </sequential>
</macrodef>