Description of problem:
Package python-flask fails to build from source in Fedora Rawhide.

Version-Release number of selected component (if applicable):
3.1.3-2.fc45

Steps to Reproduce:
fedpkg build

Additional info:
This package is tracked by Koschei. See:
https://koschei.fedoraproject.org/package/python-flask



=================================== FAILURES ===================================
_____________________ test_bad_environ_raises_bad_request ______________________
    def test_bad_environ_raises_bad_request():
        app = flask.Flask(__name__)
    
        from flask.testing import EnvironBuilder
    
        builder = EnvironBuilder(app)
        environ = builder.get_environ()
    
        # use a non-printable character in the Host - this is key to this test
        environ["HTTP_HOST"] = "\x8a"
    
        with app.request_context(environ):
            response = app.full_dispatch_request()
>       assert response.status_code == 400
E       assert 404 == 400
E        +  where 404 = <Response streamed [404 NOT FOUND]>.status_code
tests/test_reqctx.py:293: AssertionError

Reproducible: Always