If I create a regular freestyle job and use this plugin, I can set an env var and access it in a post-build step (for example, with the parameterized trigger plugin). But if I use it in a matrix job, the variable is visible in build steps, but in post-build it is not.

Repro steps:

1. Create a new matrix job
2. Use 'Generate environment variables from script' and set e.g. TEST=foo
3. Add a shell script build step and echo $TEST
4. Add a 'Trigger parameterized build' post-build step, choose another test job which is parameterized, use 'Predefined parameters' and pass something like PARAMETER=$TEST

In the downstream job, parameter will be set to the literal string $TEST. If the upstream job is just a regular freestyle project, when the downstream job triggers the parameter will actually be set to 'foo.'