My colleagues wanted some changes in our reports. So I edited the .RML files with the text editor and restarted the service openerp-server.
And my changes were never applied to the PDF reports.
So I read the documentation specific to version 5.0 on the odoo web site, I read the Q/A on this forum, and... except from a consensus about the option " Reload from attachment ".. nobody seems to have problems with .RML files modifications not being applied to the resulting .PDF files.
The facts :
- The RML report contains very specific text that only belongs to one .RML file (so the file to edit is obvious) 
- OpenERP 5.0 / linux Ubuntu 16.04.3 LTS 
- Columns `report_sxw_content_data` and `report_rml_content_data` in database table `public.ir_act_report_xml` are null 
- attachment_use is false : Reload from attachment is unticked 
The things I tried so far :
- Restart openerp-server after .RML file modification (no changes) 
- Removed or changed report lines from ir_act_report_xml (crashed odoo) 
- Check that Reload from attachment is unticked 
- Set the values `report_sxw_content_data` and `report_rml_content_data`to null (no changes, in fact they were already null) 
Does anybody have a clue about the correct method to update a .RML report ?
 
                        
@ray does it means I should stop the service and run ./openerp-server.py -u custom_module ?
As recommended by @raycarnes I stopped the open-erp server, backed-up the database and ran
./openerp-server.py --update=custom_module -d db_101209 --stop-after-init
Odoo actually tried to update the module and choked on a xml syntax error somewhere else (a previous contractor made the syntax error 3 years ago, and the module has not been updated in the last 3 years, probably). The resulting database was impossible to use..
So now either I fix the prevous guy's mistakes, or I find another way to update the .RML definitions for open-erp. There MUST be another way.. last year I upgraded the operating system and made a few minor fixes in the .RML files layout.. these changes were accepted into openerp without module updates.