veyron/services/wspr: made signature_manager_test less flaky
Squashed commit of the following:

commit d17f10c509ceea8cf536369822eebcbeb6da8af5
Author: Shyam Jayaraman <bjornick@google.com>
Date:   Tue May 13 11:29:51 2014 -0700

    made signature_manager_test less flaky

    Change-Id: I6f9a4009a5e266764c73c43e695864cb000e9fb8

Change-Id: Iee6ff60cbd02110f365935892ccf1e58a1eadd10
diff --git a/services/wspr/wsprd/lib/signature_manager_test.go b/services/wspr/wsprd/lib/signature_manager_test.go
index 52e672e..271685d 100644
--- a/services/wspr/wsprd/lib/signature_manager_test.go
+++ b/services/wspr/wsprd/lib/signature_manager_test.go
@@ -131,7 +131,7 @@
 	sm.signature(name, client)
 
 	// make last accessed go over the ttl
-	sm.cache[name].lastAccessed = sm.cache[name].lastAccessed.Add(-ttl)
+	sm.cache[name].lastAccessed = sm.cache[name].lastAccessed.Add(-2 * ttl)
 
 	// make a second call
 	sm.signature(name, client)