Fix remaining migration scripts and remove initdb/flushdb from manage.py

admin/migrations/versions/3f6994568962_.py

@@ -13,18 +13,24 @@ down_revision = '2335c80a6bc3'
 from alembic import op
 import sqlalchemy as sa
 
-from mailu import app, db
-from mailu.admin import models
+from mailu import app
+
+
+fetch_table = sa.Table(
+    'fetch',
+    sa.MetaData(),
+    sa.Column('keep', sa.Boolean())
+)
 
 
 def upgrade():
+    connection = op.get_bind()
     op.add_column('fetch', sa.Column('keep', sa.Boolean(), nullable=False, server_default=sa.sql.expression.false()))
     # also apply the current config value if set
     if app.config.get("FETCHMAIL_KEEP", "False") == "True":
-        for fetch in models.Fetch.query.all():
-            fetch.keep = True
-        db.session.commit()
-
+        connection.execute(
+            fetch_table.update().values(keep=True)
+        )
 
 
 def downgrade():