Work out what is wrong with the patch in #40006

After the patch in #40006 (closed) has been merged, I tried it in longclaw's sbws, but i had to revert to a previous commit cause all the relays were logging something like:

Jul 22 15:27:54 DEBUG Thread-2 scanner.py:253 - measure_relay - Measuring Unnamed BDCC8DD65722953D25AE15B312A900BB1CA3C4DD
Jul 22 15:27:54 DEBUG Thread-2 scanner.py:311 - measure_relay - Unable to select a second relay to help measure BDCC8DD65722953D25AE15B312A900BB1CA3C4DD (Unnamed)
Jul 22 15:27:59 INFO Thread-1 resultdump.py:804 - handle_result - Error measuring BDCC8DD65722953D25AE15B312A900BB1CA3C4DD (Unnamed) via circuit [] and destination 

I suspect the the option added is misspelled or doesn't work with stem 1.7.1, but need to check