--- run_tests.sh.orig	Thu Oct 23 00:14:08 2014
+++ run_tests.sh	Tue Oct 27 20:52:29 2015
@@ -2,7 +2,7 @@
 
 export PYTHONPATH=$(pwd)
 
-: ${VERSIONS:="python python3"}
+: ${VERSIONS:="python${MODPY_VERSION}"}
 
 for src in __init__.py bimap.py bit.py buffer.py label.py dns.py lex.py server.py digparser.py ranges.py test_decode.py
 do