I dont think it is intentional. But I could not reproduce your problems with 1.213.

The steps I tried to reproduce:
1. Execute "export MYSTERY=WORKSFORME" in shell
2. Start hudson through java -jar hudson.war
3. Create a new job
4. Add a ant builder
5. Put the following ant file into workspace
<?xml version="1.0"?>
<project name="test" default="a" basedir=".">
<target name="a">
<property environment="env" />
<echo message="Mystery=${env.MYSTERY}"/>
</target>
</project>
6. Build and check the console output:
[workspace] $ ant a
Buildfile: build.xml
a:
[echo] Mystery=WORKSFORME
BUILD SUCCESSFUL

Is there something Im missing?

Adding mail conversation

----------------------------------------------------------
From Hawkins, Keith

I must I had a typo when I tried this previously.

The symptoms now are I can set and see in the Ant echo statement an
environment variable MYSTERY.
But the environment variable CLASSPATH does not resolve. Perhaps that
is because it is being launched via java -jar hudson.war ??

Here is the build output I see from Ant:

deploy-QA-distribution:
[echo] ${env.CLASSPATH}
[echo] Can you see me

where "Can you see me" is the value I assign to MYSTERY env variable.

----------------------------------------------------------
From Erik Ramfelt

The classpath is available as the java property "java.class.path". Are
you sure that the CLASSPATH env variable is set when starting java
with "-jar Hudson.war"?

----------------------------------------------------------
From Hawkins, Keith

Yes. Because I echo it out in the run.sh in which I call java -jar
hudson.war.

----------------------------------------------------------
From Erik Ramfelt

Can you see the CLASSPATH env in the system information in Hudson? It
seems that some environment vars are not shown in the system
information but I dont know why.

Does the CLASSPATH in the ant script work properly when run outside Hudson?

----------------------------------------------------------
From Hawkins, Keith

In Hudson system information, java.class.path is just hudson.war
whereas CLASSPATH has the values I set in the run script.
If I run the Ant build outside of Hudson, the echo task of env.CLASSPATH
works as expected.

Very strange.

----------------------------------------------------------
From Erik Ramfelt

Yes, but one last question. Can you echo the env variable in a shell
in the job? ie create a shell that has "echo $CLASSPATH"

So it seems some env variables are available in the ant scripts but
not CLASSPATH, correct?

This issue also occurs on Windows batch file scripts.

In the 'System Information' of the slave the CLASSPATH variable is available under the environment variable, but as soon as you do 'echo %CLASSPATH%' this gives you this message: 'ECHO is on.' because the CLASSPATH variable is not available at all.

Im not sure whats wrong and I dont have much experience in the core parts.

Is this issue similar to the JENKINS-7442 issue?

Can someone post exact steps for a testcase that shows the problem in the latest Jenkins release? I did recently make more Jenkins-defined vars get expanded in ant build steps, but I don't think that is related here as you're talking about vars defined in the external environment.

With Jenkins 1.408, we do see most of the environment variables inherited from the slave and/or configured being available in the Ant build step with the exception of the CLASSPATH variable. Presumably, a special case?