Long time I just kept the last installation but finally it blocked me from system update, hence I was forced to de-install displaycal, which is a nightmare for a photographer.
Just trying to install it under python_3 gave me:
# python setup.py install
File "setup.py", line 258
print "Bumping version number %s ->" % \
SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Bumping version number %s ->" % \)?