Comment 3 for bug 1534090

I see the same on 14.04, even without "-" on the su.
The test also lacked the -c for the command, and "-" would need to be at the end or specified as "-l".
Also we might execute something that doesn't add output, to easen debugging (/bin/true)

Anyway - that just refines the simple test, the issue is there as reported.

Simplified test:
su testuser -c "/bin/true"