Fix job recv tagging behavior

Job recv was putting all untagged filters to the unread mailbox,
which is now what we want. This commit fixes that

crates/nu-protocol/src/engine/jobs.rs

@@ -273,7 +273,7 @@ impl Mailbox {
             while waited_so_far < timeout {
                 let (tag, value) = self.receiver.recv_timeout(timeout - waited_so_far)?;
 
-                if filter_tag.is_some() && filter_tag == tag {
+                if filter_tag.is_none() || filter_tag == tag  {
                     return Ok(value);
                 } else {
                     self.ignored_mail.add((tag, value));