db: introduce migration step after 93834966ae01 dropped non-nullable inherit_default_permissions The database migration step was lazily and naively skipped ... but that turns out to be a problem when new users are added. In the database, the original column 'inherit_default_permissions' was marked as non-nullable without default value. In the Kallithea code after commit 93834966ae01, the column 'inherit_default_permissions' was no longer known, and thus not given a value when new users are added. As a result, the database complained: IntegrityError: (psycopg2.errors.NotNullViolation) null value in column "inherit_default_permissions" violates not-null constraint Fix that now by adding an appropriate db migration step to actually remove the columns. Use meta reflection to check if columns exist before running the upgrade step. The upgrade step only has to be run if it is an old database - not if it has been created after the schema changes were introduced. For the downgrade step, make sure to set a default value for non-nullable columns.