ovsdb-cluster: Add comment to test.
I thought I had added this while revising a previous patch but oops.
Fixes: ("tests: Fix cluster torture test.")
@@ -149,6 +149,7 @@ ovsdb|WARN|schema: changed 2 columns in 'OVN_Southbound' database from ephemeral
sleep 2
echo "waiting for ovn-sbctl processes to exit..."
+ # Use file instead of var because code inside "while" runs in a subshell.
echo 0 > phase
i=0
(while :; do echo; sleep 1; done) | while read; do
