[evolution] Avoid crash on folder rename

[Milan Crha <mcrha src gnome org>]

commit 8e5ed2e6458bf04d81c2a355f20a4b80f91548c8
Author: Milan Crha <mcrha redhat com>
Date:   Tue Jul 10 14:59:21 2012 +0200

    Avoid crash on folder rename

 mail/e-mail-backend.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/mail/e-mail-backend.c b/mail/e-mail-backend.c
index e0213f6..164e5a0 100644
--- a/mail/e-mail-backend.c
+++ b/mail/e-mail-backend.c
@@ -592,7 +592,7 @@ mail_backend_folder_renamed_cb (MailFolderCache *folder_cache,
 			e_source_mail_submission_get_sent_folder (
 			E_SOURCE_MAIL_SUBMISSION (extension));
 
-		if (class->equal_folder_name (sent_folder_uri, old_uri)) {
+		if (sent_folder_uri && class->equal_folder_name (sent_folder_uri, old_uri)) {
 			GError *error = NULL;
 
 			e_source_mail_submission_set_sent_folder (