[evolution] Crash under e_mail_folder_find_duplicate_messages_sync()

[Milan Crha <mcrha src gnome org>]

commit 44743d4e7482861fb711a9b79961dbf386025e40
Author: Milan Crha <mcrha redhat com>
Date:   Mon Jun 13 12:35:41 2016 +0200

    Crash under e_mail_folder_find_duplicate_messages_sync()
    
    Check whether the message still exists, before accessing the message info
    structure, to avoid a crash.
    
    This had been reported downstream at:
    https://bugzilla.redhat.com/show_bug.cgi?id=1344888

 libemail-engine/e-mail-folder-utils.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/libemail-engine/e-mail-folder-utils.c b/libemail-engine/e-mail-folder-utils.c
index 89d773c..50eed64 100644
--- a/libemail-engine/e-mail-folder-utils.c
+++ b/libemail-engine/e-mail-folder-utils.c
@@ -793,6 +793,9 @@ e_mail_folder_find_duplicate_messages_sync (CamelFolder *folder,
                const gchar *digest;
 
                info = camel_folder_get_message_info (folder, key);
+               if (!info)
+                       continue;
+
                message_id = camel_message_info_message_id (info);
                flags = camel_message_info_flags (info);