Tests: eliminate race in proxy_cache_lock.t startup.
diff --git a/proxy_cache_lock.t b/proxy_cache_lock.t
index 4489452..6b47c60 100644
--- a/proxy_cache_lock.t
+++ b/proxy_cache_lock.t
@@ -76,6 +76,7 @@
 plan(skip_all => 'no proxy_cache_lock') if $@;
 
 $t->plan(19);
+$t->waitforsocket('127.0.0.1:8081');
 
 ###############################################################################
 
@@ -199,6 +200,8 @@
 			last if /^\x0d?\x0a?$/;
 		}
 
+		next unless $uri;
+
 		sleep(1);
 
 		$num++;