missleading error message for iperf2 test

[bltierney]

This works fine:
pscheduler task --tool iperf2 throughput --dest hostname

But this gives an error:
pscheduler task --tool iperf2 throughput --mss 4096 --dest hostname
Failed to post task: Unable to complete request: No tool in common among the participants:

That error message is very misleading. I'm guessing the iperf2 arg parsing code does not include -M ?

Also, iperf2 supports -mss same as iperf3 with the same "-M" flag, so the no reason the test should fail.

[mfeit-internet2]

The message might be unclear, but it isn't misleading. It means that none of the tool plugins on any of the hosts involved said they could run the test as specified.

Whoever wrote the iperf2 plugin didn't make it understand the mss parameter, either because uperf2 didn't support it at the time or because of an oversight.

I'll put this in the pipeline for 5.1.

[bltierney]

to me a better error message for this situation would be:
Failed to post task: Unable to complete request: No tool in common among the participants, or tool args not supported

[mfeit-internet2]

#384 fixes this.