models: Modify behavior of Series.received_all

models: Modify behavior of Series.received_all

At the moment, Series.received_all is only true is the number of patches
received exactly matches the expected number of patches. However, there
are cases where there may in fact be more patches in the final series
than expected. For example, one could send patches with a subject of
'PATCH 5/4' in-reply-to an original four patch series. The parser
handles this correctly, so the 'received_all' property should too.

We still need to support patterns like '5/n', which are in use and do
not appear to be supported since 'c21b305'. This can be done at a later
stage.

Signed-off-by: Stephen Finucane <stephen@that.guru>
Tested-by: Daniel Axtens <dja@axtens.net>