New Python bindings (notmuch2 module) fail to exclude tags

["Jorge P. de Morais Neto" <jorge+list@disroot.org>]

Hi.  I am trying to migrate my Python3 script to the new Python bindings
(notmuch2 module).  However, I cannot obtain a count of messages
matching a query excluding messages that have an exclude tag.  From the
command line:
    $ notmuch count 'is:.bf_spam'
    0

The CLI command correctly counts zero messages having '.bf_spam' tag,
because all such messages also have the excluded 'spam' tag.  But from
Python:

$ python3
Python 3.7.3 (default, Jul 25 2020, 13:03:44) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import notmuch2
>>> nm_db=notmuch2.Database()
>>> nm_db.count_messages('is:.bf_spam', exclude_tags=('spam',))
379
>>> nm_db.count_messages('is:.bf_spam', exclude_tags=('spam',), omit_excluded=nm_db.EXCLUDE.FALSE)
379
>>> nm_db.count_messages('is:.bf_spam', exclude_tags=('spam',), omit_excluded=nm_db.EXCLUDE.TRUE)
379
>>> nm_db.count_messages('is:.bf_spam', exclude_tags=('spam',), omit_excluded=nm_db.EXCLUDE.ALL)
379
>>> nm_db.count_messages('is:.bf_spam', exclude_tags=('spam',), omit_excluded=nm_db.EXCLUDE.FLAG)
379

Am I doing something wrong?

Regards

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