tests: Fix flaky test "multi-vtep SB Chassis encap updates"

Signed-off-by: Xavier Simonart <xsimonar@redhat.com>
Acked-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Mark Michelson <mmichels@redhat.com>

tests/ovn.at

@@ -26744,7 +26744,11 @@ ovs-vsctl add-br br-phys
 ovn_attach n1 br-phys 192.168.0.1 24 geneve
 
 # Get the encap rec, should be just one - with geneve/192.168.0.1
-encap_rec=$(ovn-sbctl --data=bare --no-heading --column encaps list chassis hv1)
+# Skip initial null encap
+OVS_WAIT_UNTIL(
+  [encap_rec=$(ovn-sbctl --bare --no-heading --columns encaps list chassis hv1)
+  echo "encap_rec = $encap_rec"
+  test $encap_rec])
 
 # Set multiple IPs
 as hv1
@@ -26753,9 +26757,10 @@ ovs-vsctl \
 
 # Check if the encap_rec changed - should have, no need to
 # compare the exact values.
-encap_rec_mvtep=$(ovn-sbctl --data=bare --no-heading --column encaps list chassis hv1)
-
-AT_CHECK([test "$encap_rec" != "$encap_rec_mvtep"], [0], [])
+OVS_WAIT_UNTIL(
+  [encap_rec_mvtep=$(ovn-sbctl --bare --no-heading --columns encaps list chassis hv1)
+  echo "encap_rec_mvtep = $encap_rec_mvtep"
+  test "$encap_rec" != "$encap_rec_mvtep"])
 
 # now, wait for a couple of secs -  should be enough time, I suppose.
 sleep 2