TBR: longevity tests: retry syncgroup join forever.

Change-Id: Ie9149a4a8a10f1ad8617e055f6ddfd2705efe580
diff --git a/services/syncbase/longevity_tests/client/util.go b/services/syncbase/longevity_tests/client/util.go
index 0fc49d1..c4351e8 100644
--- a/services/syncbase/longevity_tests/client/util.go
+++ b/services/syncbase/longevity_tests/client/util.go
@@ -88,7 +88,7 @@
 				// TODO(nlacasse): Parameterize number of retries.  Exponential
 				// backoff?
 				var joinErr error
-				for i := 0; i < 10; i++ {
+				for {
 					_, joinErr = sg.Join(ctx, sgModel.HostDevice.Name, nil, wire.SyncgroupMemberInfo{})
 					if joinErr == nil {
 						syncgroups = append(syncgroups, sg)