Fix DockerTrustSuite SetUpTest

This hopefully makes DockerTrustSuite.SetUpTest
less flaky.

Increased the number of attempts to check
if Notary is available before giving up.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 910a5fc2348b934dcb126c021721305d5316c7c0
Component: engine

components/engine/integration-cli/trust_server.go

@@ -106,7 +106,7 @@ func newTestNotary(c *check.C) (*testNotary, error) {
 	}
 
 	// Wait for notary to be ready to serve requests.
-	for i := 1; i <= 5; i++ {
+	for i := 1; i <= 20; i++ {
 		if err = testNotary.Ping(); err == nil {
 			break
 		}