composer: Install composer on Jenkins: Composer could not find the config file: C:\ProgramData\ComposerSetup\bin

I have an Ant build script that is trying to execute Composer install but I get this error when executed through Jenkins:

     [exec] Composer could not find the config file: C:\ProgramData\ComposerSetup\bin
     [exec] To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
     [exec] Result: 1
     [echo] composer update complete

Here is the target from Ant:

<target name="self-update"
        if="composer.self-update"
        unless="composer.installed"
        description="Self-update Composer">
    <echo message="Self-updating composer" level="debug"/>
    <exec executable="${composer.phar}">
        <arg value="self-update" />
        <arg value="--quiet" />
        <arg value="--no-interaction" />
    </exec>
    <echo message="composer self-update complete" level="debug"/>
</target>

However, this works fine when running the Ant build locally.

Some people say to delete the environment variables that the composer installer sets; however it does not seem to change anything.