[gnome-shell] gdm: use password authentication if all schemes are disabled

[Ray Strode <halfline src gnome org>]

commit 58827ba36d7b88a3c1be6bbaa5b6e07a4e6fa15c
Author: Ray Strode <rstrode redhat com>
Date:   Wed Jul 1 11:18:44 2015 -0400

    gdm: use password authentication if all schemes are disabled
    
    This prevents a traceback, at least.

 js/gdm/util.js | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/js/gdm/util.js b/js/gdm/util.js
index b594da4fd..bae46bfe0 100644
--- a/js/gdm/util.js
+++ b/js/gdm/util.js
@@ -419,6 +419,11 @@ var ShellUserVerifier = new Lang.Class({
             this._defaultService = SMARTCARD_SERVICE_NAME;
         else if (this._haveFingerprintReader)
             this._defaultService = FINGERPRINT_SERVICE_NAME;
+
+        if (!this._defaultService) {
+            log("no authentication service is enabled, using password authentication");
+            this._defaultService = PASSWORD_SERVICE_NAME;
+        }
     },
 
     _startService: function(serviceName) {