travis: run nosetests-2.7 (#6113)

Author: weizhouapache

tools/travis/script.sh

@@ -30,7 +30,7 @@ set -e
 
 for suite in "${TESTS[@]}" ; do
   echo "Currently running test: $suite"
-  time nosetests --with-xunit --xunit-file=integration-test-results/$suite.xml --with-marvin --marvin-config=setup/dev/advanced.cfg test/integration/$suite.py -s -a tags=advanced,required_hardware=false --zone=Sandbox-simulator --hypervisor=simulator || true ;
+  time nosetests-3.4 --with-xunit --xunit-file=integration-test-results/$suite.xml --with-marvin --marvin-config=setup/dev/advanced.cfg test/integration/$suite.py -s -a tags=advanced,required_hardware=false --zone=Sandbox-simulator --hypervisor=simulator || true ;
 done
 
 python3 ./tools/travis/xunit-reader.py integration-test-results/