Fix display exception

When global language conventions clash with "local" project conventions, basically all standards say to use the local one.

In the first lines of PEP8: 
> Many projects have their own coding style guidelines. In the event of any conflicts, such project-specific guides take precedence for that project. 

A little later:
>  Some other good reasons to ignore a particular guideline:
* When applying the guideline would make the code less readable, even for someone who is used to reading code that follows this PEP.
* To be consistent with surrounding code that also breaks it (maybe for historic reasons) -- although this is also an opportunity to clean up someone else's mess (in true XP style). 

So I'd say to prefer Odoo consistency at the moment, and push for a change in Odoo conventions at the same time, as some of those are really horrible.