Symptom: Y-cable protection groups execute an unexpected double switch.

Conditions: This can occur when the protect trunk span of the Y-cable
protection group is fitted with a physical loopback cable and a brief
alarm condition is injected into the working span. The protection group
will switch to protect when the alarm is raised and then immediately
revert to working when the alarm is cleared.  

The alarm condition must clear quickly; the symptom is most repeatable
when the alarm clears within one second.

This symptom has been observed when the card mode is Transparent.