[Pkg-mailman-hackers] Bug#919145: mailman3: stretch-backports dependencies can not be satisfied with python3-alembic from backports

[Sampo Sorsa]

Package: mailman3
Version: 3.2.0-4~bpo9+1

Dear Maintainer,

The mailman3 dependencies can not be satisfied with python3-alembic from stretch-backports:

Package: mailman3
Depends: python3-alembic, python3-sqlalchemy (>= 1.2.3)

Package: python3-alembic
Version: 1.0.0-2~bpo9+1
Depends: python3-sqlalchemy (>= 1.0~), python3-sqlalchemy (<< 1.1)

The python3-sqlalchemy dependency is conflicting. The only way to resolve this is to downgrade python3-alembic to stretch version:

Package: python3-alembic
Version: 0.8.8-2
Depends: python3-sqlalchemy (>= 0.7.6)

Perhaps this bug should be filed under python3-alembic to request backports upgrade (although buster is 1.0.0-2 too), but I wanted to make both maintainers and users of mailman3 aware of the issue. Please refile if necessary.

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Sampo Sorsa