One problem with hexdigest is that it's longer and the column was
created as binary(16). We don't have a mechanism to run migrations on
this table, so we use UNHEX in SQL to have the equivalent as digest()
from hexdigest()
Co-authored-by: Jérome Perrin <jerome@nexedi.com>

also str representation of unicode character is different.

this is not used and cause a SyntaxWarning

page templates unicode resolver already takes care of coercing when
needed and this is directly compatible with python2 and python3
Co-authored-by: Kazuhiko SHIOZAKI <kazuhiko@nexedi.com>