'American Ultra' French release date has been moved forward to August 26, 2015! We will no longer have to wait until September! :-)
Allociné, French version of IMDb, updated its page with the new date - and the distributor, Metropolitan Filmexport, kindly confirmed it to me. :-)
Time to re-re-re-re watch the trailer - here's with French subtitles. Enjoy!
The 'American Ultra' release dates so far - schedule page.
Thanks to @ItsOktobeYou