Merge remote-tracking branch 'syncthing/pr/2117'

* syncthing/pr/2117:
  Disable testing upgrade endpoint because it fails when disconnected

test/http_test.go

@@ -40,7 +40,6 @@ var jsonEndpoints = []string{
 	"/rest/system/error",
 	"/rest/system/ping",
 	"/rest/system/status",
-	"/rest/system/upgrade",
 	"/rest/system/version",
 }