Seems like consume_events() didn't work properly, i.e. in some cases it
didn't see the latest events and failed to consume them. So, the
IncomingMsg event from receiving DC_MAILINGLIST stayed in the events
channel, which made this fail:
```rust
// Check that no notification is displayed for blocked mailing list message.
while let Ok(event) = t.evtracker.try_recv() {
assert!(!matches!(event.typ, EventType::IncomingMsg { .. }));
}
```
Fix it by explicitly waiting for the first IncomingMsg event.
This way no temporary rows are created and it is easier to maintain
because UPDATE statement is right below the INSERT statement,
unlike `merge_messages` function which is easy to forget about.
* save webxdc-updates for not yet downloaded messages, that are probably webxdc instances then
* test webxdc updates received while instance is not yet downloaded
* keep msg_id on downloading messages
keeping msg_id on downloading messages
has the advantage that webxdc updates and other references to the msg_id
can be processed as usual.
if a message expands to multiple msg_id,
the last one is kept,
however, this does not affect webxdc at all.
(alternatives may be to update `msgs_status_updates`
but that seems more complicated and even less elegant,
another alternative would be to use different keys (eg. `rfc274_mid`),
but that also seems not to be much easier and would waste space as well.
also both alternatives would need adaption for other foreign keys)
* update CHANGELOG
* do not emit WebxdcStatusUpdate event in case the message is not yet downloaded
* move DELETE/UPDATE to an transaction
* make merge_msg_id() a little less confusing
* use some webxdc-update-param from placeholder
(the placeholder may be updated,
the just downloaded messages is not)
* more precise function name
* test not directly downloading status updates
* test not directly downloading mdn
