Remove volatile-attribute-related code, it has nothing to do on such class.
Rename the flag used to know wether _abort or _finish has to be called.
Initialise that flag during _begin.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13666 20353a03-c40f-0410-a6d1-a30d3c3de9de