… non-call Message-ID

In-Reply-To may refer to non-call message
as we do not control the sender.
It may also happen that call message
was received by older version and processed
as text, in which case correct In-Reply-To
appears to be referring to the text message.

Any control information from the message
should only be downloaded when the message
is fully downloaded to avoid processing it twice.
Besides, "partial" messages may actually be full messages
with an error that are only processed as partial
to add a message bubble allowing to download the message later.