[with patch, positive review] dsage.setup() -- very serious bug

[was]

Do

sage: dsage.setup()

and take all the defaults, then do it again immediately but enter a non-default hostname. BOOM! See  http://sage.pastebin.com/m1ff54979 for a log of this.

The error involves sqlalchemy table insertion; somebody messed up:

    739         if not self.non_primary and '_class_state' in self.class_.__dict__ and (self.entity_name in self.class_._class_state.mappers):
--> 740              raise exceptions.ArgumentError("Class '%s' already has a primary mapper defined with entity name '%s'.  Use non_primary=True to create a non primary Mapper.  clear_mappers() will remove *all* current mappers from all classes." % (self.class_, self.entity_name))
    741 
    742         def extra_init(class_, oldinit, instance, args, kwargs):

ArgumentError: Class '<class 'sage.dsage.database.job.Job'>' already has a primary mapper defined with entity name 'None'.  Use non_primary=True to create a non primary Mapper.  clear_mappers() will remove *all* current mappers from all classes.
sage: 

[yi]

add clear_mapper call to db_config.py

[gfurnish]

DSage is completely broken in 3.0.2 and 3.0.3!!!!! Can you post some patches so that we can run it out of the box?

[yi]

What exactly is wrong with this patch? Use this ticket to provide feedback about this particular patch and the issue it aims to fix. File a separate bug if dsage doesn't run for you and include some actual repro steps.

[mabshoff]

Merged in Sage 3.0.3.final