Use multiple base urls for simplestreams

environs/ec2/ec2.go

+// Copyright 2011, 2012, 2013 Canonical Ltd.
+// Licensed under the AGPLv3, see LICENCE file for details.
+
 package ec2
 
 import (
         "fmt"
         "io/ioutil"
         "launchpad.net/goamz/aws"
         "launchpad.net/goamz/ec2"
         "launchpad.net/goamz/s3"
         "launchpad.net/juju-core/constraints"
         "launchpad.net/juju-core/environs"
@@ skipping 240 matching lines @@
         var err error
         for a := shortAttempt.Start(); a.Next(); {
                 _, err = e.loadState()
                 if err != nil {
                         break
                 }
         }
         if err == nil {
                 return fmt.Errorf("environment is already bootstrapped")
         }
-        if _, notFound := err.(*environs.NotFoundError); !notFound {
+        if !environs.IsNotFoundError(err) {
                 return fmt.Errorf("cannot query old bootstrap state: %v", err)
         }
 
         possibleTools, err := environs.FindBootstrapTools(e, cons)
         if err != nil {
                 return err
         }
         inst, err := e.startInstance(&startInstanceParams{
                 machineId:     "0",
                 machineNonce:  state.BootstrapNonce,
@@ skipping 758 matching lines @@
                 }
                 var data []byte
                 data, err = ioutil.ReadAll(resp.Body)
                 if err != nil {
                         continue
                 }
                 return strings.TrimSpace(string(data)), nil
         }
         return
 }