Docker image build error: "SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Setting debug mode")?"

Someone pinged me encountering the following issue with building the docker image:

=======
scons
scons: Reading SConscript files ...
  File "/home/heiko/libzafl/SConscript", line 9

    print "Setting debug mode"

          ^

SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Setting debug mode")?
=======

Any ideas?