cubicweb #2716163 i18n doesn't work for entitities, etc. [deprecated]

It is currently not possible to translate part of the user interface, more specifically entity names. Try using non-ASCII characters in a *.po file under # singular and plural forms for each entity type.

The error looks like:

une erreur est survenue
ValueError: can't deal with non-ascii based characters
can't deal with non-ascii based characters
File /usr/lib/python2.7/dist-packages/cubicweb/web/application.py, line 445, function core_handle:
  result = controller.publish(rset=rset)
[...]
File /usr/lib/pymodules/python2.7/logilab/common/textutils.py, line 103, function unormalize:
  raise ValueError("can't deal with non-ascii based characters")
CubicWeb version: 3.15.9
Cube pouet version: 0.1.0
Cube card version: 0.3.0
prioritynormal
typebug
done in<not specified>
load0.000
load left0.000
closed by<not specified>