tahoe-lafs/misc/build_helpers/test-darcs-boringfile.py

#!/usr/bin/env python

import sys
from subprocess import Popen, PIPE

cmd = ["darcs", "whatsnew", "-l"]
p = Popen(cmd, stdout=PIPE)
output = p.communicate()[0]
print output
if output == "No changes!\n":
    sys.exit(0)
sys.exit(1)