improve error message for l0 test.
improve error message for l0 test.

Microsoft/vsts-agent,lkillgore/vsts-agent,Microsoft/vsts-agent,lkillgore/vsts-agent,kasubram/vsts-agent,kasubram/vsts-agent,lkillgore/vsts-agent,lkillgore/vsts-agent,Microsoft/vsts-agent,kasubram/vsts-agent,Microsoft/vsts-agent,kasubram/vsts-agent