subant failonerror subtleties

<target name="all-release" >
    <subant target="sub-release" failonerror="true">
        <fileset dir="." includes="*/build.xml" />
    </subant>
   </target>

<taskdef resource="net/sf/antcontrib/antlib.xml">
    <classpath>
        <pathelement location="lib/ant-contrib-1.0b3.jar"/>
    </classpath>
</taskdef>

<target name="all-release">
    <for keepgoing="true" param="file">
        <path>
            <fileset dir="." includes="*/build.xml" />
        </path>
        <sequential>
            <ant antfile="@{file}" target="sub-release" />
        </sequential>
    </for>
</target>

$ ant all-release
Buildfile: build.xml

all-release:
     [echo] /work/Scratch/dir1/build.xml

sub-release:
     [echo] dir1
     [echo] /work/Scratch/dir2/build.xml

sub-release:
     [echo] dir2
      [for] /work/Scratch/dir2/build.xml: The following error occurred while executing this line:
      [for] /work/Scratch/build.xml:17: The following error occurred while executing this line:
      [for] /work/Scratch/dir2/build.xml:6: dir2 failed
     [echo] /work/Scratch/dir3/build.xml

sub-release:
     [echo] dir3

BUILD FAILED
/work/Scratch/build.xml:11: Keepgoing execution: 1 of 3 iterations failed.

Total time: 0 seconds

<taskdef name="try" classname="ise.antelope.tasks.TryTask"/>
....
<try break="false" printmessage="true" >
   <antcall target="xmlValidate" />
   <antcall target="runJunit" />
   <antcall target="..." />
   <catch>
      <property name="haderrors" value="true"/>
   </catch>
</try>
<fail message="FAILED" if="haderrors" />