Commit 3ec5d2d6ed added a Python-based
name server (bin/tests/system/digdelv/ans8/ans.py) to the "digdelv"
system test, but did not update bin/tests/system/Makefile.am to ensure
Python is present in the test environment before the "digdelv" system
test is run. Update bin/tests/system/Makefile.am to enforce that
requirement.