bug#15361: git send-email creates one report per patch

[Stefan Monnier]

> I did actually implement that, but it replies on the message-id getting
> into the bug database index, which is only updated every 5(?) minutes or
> so. When a bunch of emails arrive all at the same time, as from git, it
> cannot work.
> To fix this, need to force message-id into the index immediately after a
> new report arrives. I don't know how much work that is, or when I'll
> have time to look at it.

Doing it more promptly won't be always sufficient: the message may
arrive in a different order.  So in order to make it work reliably, we
should do something more devious, such as:
- postpone processing of messages with an "in-repy-to" that's not found
  in the message-id database.
- when we receive a message with an "in-reply-to" that's not found in
  the message-id database, allocate a new bug-nb for it and add that
  message-id to the database.  Then when a message arrives, don't only
  look for its in-reply-to in the database but also its message-id!
  And then figure out a way to handle the "deeper" threading case where
  we first receive the grand-child, then the grand parent, and only
  third the in-between.
Postponing, seems like a "cheap" way to solve 99% of the problem.


        Stefan