lib-index: mail_index_sync_next() didn't always return expunges sorted Maildir and mbox formats were using index_sync_changes_read(), which assumed that they were sorted. So some of the intended expunges weren't actually always being done. This mainly affected when expunges were being done simultaneously by multiple processes or by pipelined commands. For example: printf "a select inbox\nb uid move 2 Trash\nc uid move 1 Trash\nd logout\n" | ./imap

--- a/src/lib-index/mail-index-sync.c	Tue Feb 16 18:05:59 2016 +0100
+++ b/src/lib-index/mail-index-sync.c	Sun Feb 21 03:40:48 2016 +0200
@@ -206,6 +206,7 @@
 	i_array_init(&ctx->sync_list, keyword_count + 2);
 
 	if (array_is_created(&sync_trans->expunges)) {
+		mail_index_transaction_sort_expunges(sync_trans);
 		synclist = array_append_space(&ctx->sync_list);
 		synclist->array = (void *)&sync_trans->expunges;
 	}