Dashboard export/import doesn't work in v1.3

Getting the following error during export > import of dashboards.

This Session's transaction has been rolled back due to a previous exception during flush. 
To begin a new transaction with this Session, first issue Session.rollback(). 
Original exception was: Dataset [reporting].[public].[lookup] already exists 
(Background on this error at: http://sqlalche.me/e/13/7s2a)

Expected results

Prior 1.3 recent update, we were able to do the following.

Environment setup and workflow:

1. We have 2 environments [dev, prod]
2. We do our dashboard development in dev environment
3. Once dashboard looks good, we deploy the changes to prod by doing following 3 steps 3.1 Export dashboard from dev 3.2 Import dashboard to prod 3.3 Replace the slug for the new dashboard so that the users doesn’t need to update their bookmarks

Actual results

Gets the following error : Dataset %s already exists

{"asctime": "2021-08-19 15:00:13,977", "threadName": "Dummy-10563", "request_id": "803a6e3e-0ea2-488a-846b-f6550e4ff4fd", "levelname": "ERROR", "name": "superset.views.core", "lineno": 695, "message": "Dataset [reporting].[public].[lookup] already exists", "exc_info": "Traceback (most recent call last):
  File "/app/superset/views/core.py", line 680, in import_dashboards
    {import_file.filename: import_file.read()}, database_id
  File "/app/superset/dashboards/commands/importers/v0.py", line 353, in run
    import_dashboards(db.session, content, self.database_id)
  File "/app/superset/dashboards/commands/importers/v0.py", line 323, in import_dashboards
    new_dataset_id = import_dataset(table, database_id, import_time=import_time)
  File "/app/superset/datasets/commands/importers/v0.py", line 110, in import_dataset
    database_id,
  File "/app/superset/datasets/commands/importers/v0.py", line 204, in import_datasource
    session.flush()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/scoping.py", line 163, in do
    return getattr(self.registry(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 2536, in flush
    self._flush(objects)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 2678, in _flush
    transaction.rollback(_capture_exception=True)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    with_traceback=exc_tb,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 2638, in _flush
    flush_context.execute()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/unitofwork.py", line 422, in execute
    rec.execute(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/unitofwork.py", line 589, in execute
    uow,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/persistence.py", line 213, in save_obj
    ) in _organize_states_for_save(base_mapper, states, uowtransaction):
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/persistence.py", line 387, in _organize_states_for_save
    mapper.dispatch.before_update(mapper, connection, state)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/event/attr.py", line 322, in __call__
    fn(*args, **kw)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/events.py", line 719, in wrap
    fn(*arg, **kw)
  File "/app/superset/connectors/sqla/models.py", line 1654, in before_update
    raise Exception(get_dataset_exist_error_msg(target.full_name))
Exception: Dataset [reporting].[public].[lookup] already exists"}


{"asctime": "2021-08-19 15:00:13,981", "threadName": "Dummy-10563", "request_id": "803a6e3e-0ea2-488a-846b-f6550e4ff4fd", "levelname": "ERROR", "name": "superset.views.base", "lineno": 444, "message": "This Session's transaction has been rolled back due to a previous exception during flush. To begin a new transaction with this Session, first issue Session.rollback(). Original exception was: Dataset [reporting].[public].[lookup] already exists (Background on this error at: http://sqlalche.me/e/13/7s2a)", "exc_info": "Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/local/lib/python3.7/site-packages/flask_appbuilder/security/decorators.py", line 109, in wraps
    return f(self, *args, **kwargs)
  File "/app/superset/utils/log.py", line 241, in wrapper
    value = f(*args, **kwargs)
  File "/app/superset/views/core.py", line 707, in import_dashboards
    databases = db.session.query(Database).all()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3373, in all
    return list(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3535, in __iter__
    return self._execute_and_instances(context)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3557, in _execute_and_instances
    querycontext, self._connection_from_session, close_with_result=True
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3572, in _get_bind_args
    mapper=self._bind_mapper(), clause=querycontext.statement, **kw
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3550, in _connection_from_session
    conn = self.session.connection(**kw)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 1141, in connection
    execution_options=execution_options,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 1147, in _connection_for_bind
    engine, execution_options
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 409, in _connection_for_bind
    self._assert_active()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 296, in _assert_active
    code="7s2a",
sqlalchemy.exc.InvalidRequestError: This Session's transaction has been rolled back due to a previous exception during flush. To begin a new transaction with this Session, first issue Session.rollback(). Original exception was: Dataset [reporting].[public].[lookup] already exists (Background on this error at: http://sqlalche.me/e/13/7s2a)"}
{"asctime": "2021-08-19 15:00:13,984", "threadName": "Dummy-10563", "request_id": "803a6e3e-0ea2-488a-846b-f6550e4ff4fd", "levelname": "INFO", "name": "maf", "lineno": 61, "message": "response for POST https://reports-uat.storyboard.nielsen.com/superset/import_dashboards/ 500 INTERNAL SERVER ERROR", "method": "POST", "url": "https://reports-uat.storyboard.nielsen.com/superset/import_dashboards/", "status": "500 INTERNAL SERVER ERROR"}

Screenshots

How to reproduce the bug

1. set “VERSIONED_EXPORT”: True feature flag
2. Start superset with examples
3. Export an existing dashboard
4. Import it back to the same instance
5. See error

Environment

(please complete the following information):

• superset version: 1.3
• python version: 3.7.9
• node.js version: v14.15.5
• any feature flags active:

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven’t found one similar.

Additional context

Tracked down the error to this pull request #15909, and specifically this change

[vivek-kandhvar]

We have the same issue after upgrading superset from 1.2.0 to 1.3.0. We haven’t touched the flag “VERSIONED_EXPORT”, and it is still False which is the default.

This used to work in 1.2.0 without any issue. Now we end up with this error "Dataset <xyz> already exists!"

[amitmiran137]

this is a user mistake by turning off the feature flag and moved to old mechanism: https://github.com/apache/superset/pull/16569