practracker: Be compatible with python2 which is used by travis/jenkins.

scripts/maint/practracker/practracker.py

@@ -18,6 +18,8 @@ the source code and then get saved in the repository for ever after:
   $ python3 ./scripts/maint/practracker/practracker.py . > ./scripts/maint/practracker/exceptions.txt
 """
 
+from __future__ import print_function
+
 import os, sys
 
 import metrics

scripts/maint/practracker/problem.py

@@ -7,6 +7,8 @@ problem is worse than a registered exception so that it only warns when things
 get worse.
 """
 
+from __future__ import print_function
+
 import os.path
 import sys