Jenkins AntExec plugin not working with ant contrib - ant

Question

I have latest Jenkins running on Windows 2003 server.
Under, manage Jenkins:
I have IBM JDK set
I have ant: org.apache.ant_1.7.1.v20100518-1145 set as ant home
I have Jenkins AntExec plug in installed.
I have ant-contrib-0.6.jar inside anthome/lib.
I created a job, and added a build step, Execute Apache Ant, and I have this:
<echo> java home = ${JAVA_HOME}</echo>
<taskdef resource="net/sf/antcontrib/antlib.xml"/>
<project name="Test">
<description> Sample bulid file </description>
<target name="first">
<echo message="The first five letters of the alphabet are:"/>
<antcontrib:for list="a,b,c,d,e" param="letter">
<sequential>
<echo>Letter #{letter}</echo>
</sequential>
</antcontrib:for>
</target>
</project>
when I run build, it fails.
antexec_build.xml:
[echo] ant home = ${ANT_HOME}
[echo] java home = ${JAVA_HOME}
BUILD FAILED
C:\Program Files (x86)\Jenkins\jobs\MCSOWelcome\workspace\antexec_build.xml:13: Problem: failed to create task or type project
Cause: The name is undefined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any <presetdef>/<macrodef> declarations have taken place.
I have tried many different things, no luck. Please suggest

Answer 1

AntExec comes bundled with AntContrib. You do not need to add or define it. On the contrary, to disable it, you need to open 2 Advanced... dialogs before you get the option.
What you need to do though, is use antcontrib namespace.
For example, to use for, type:
<antcontrib:for>

Answer 2

I ran into the same problem (I got the same error message: Problem: failed to create task or type project), although I didn't use <antcontrib:for> tag.
If you type some code to the Script source field at the Project configuration > Execute Apache Ant, the plugin doesn't use it as an entire Ant script file, but it inserts into a template script. It appears if you choose to keep the buildfile (Advanced view at Execute Ant Build step). In this case the generated antexec_build.xml Ant script will not be deleted from the Workspace of the Project after the build.
The issue is reproducable with this simple script typed in Script source:
<project>
</project>
The generated antexec_build.xml:
<?xml version="1.0" encoding="utf-8"?>
<project default="antexec_build.xml" xmlns:antcontrib="antlib:net.sf.antcontrib" basedir=".">
<!-- Read additional properties -->
<property file="antexec_build.xml.properties"/>
<!-- Make environment variables accesible via ${env.VARIABLE} by default -->
<property environment="env"/>
<target name="antexec_build.xml">
<!-- Default target entered in the first textarea - begin -->
<project>
</project>
<!-- Default target entered in the first textarea - end -->
</target>
</project>
So that, a solution would be that only include the Ant script that you intend to insert into the <target></target> tag.