narrow: don't compress the bundle2 when sending 'error:abort'

Authored by pulkit.

Description

narrow: don't compress the bundle2 when sending 'error:abort'

This is similar to waht getbundle() does and also explicitly specifies that we
should get a compressed bundle2 in normal cases when not sending 'error:abort'.

Differential Revision: https://phab.mercurial-scm.org/D4934