--- debconffilter.py.orig
+++ debconffilter.py
@@ -20,6 +20,7 @@
 import sys
 import os
 import fcntl
+import signal
 import errno
 import subprocess
 import re
@@ -152,6 +153,10 @@
             os.environ['HOME'] = '/root'
             for key, value in extra_env.iteritems():
                 os.environ[key] = value
+            # Python installs a SIGPIPE handler by default. This is bad for
+            # non-Python subprocesses, which need SIGPIPE set to the default
+            # action or else they won't notice if the debconffilter dies.
+            signal.signal(signal.SIGPIPE, signal.SIG_DFL)
 
         self.subp = subprocess.Popen(
             command, stdin=subprocess.PIPE, stdout=subprocess.PIPE,

--- filteredcommand.py.orig
+++ filteredcommand.py
@@ -3,6 +3,7 @@
 
 import sys
 import os
+import signal
 import subprocess
 import debconf
 try:
@@ -109,6 +110,11 @@
             def subprocess_setup():
                 for key, value in env.iteritems():
                     os.environ[key] = value
+                # Python installs a SIGPIPE handler by default. This is bad
+                # for non-Python subprocesses, which need SIGPIPE set to the
+                # default action or else they won't notice if the
+                # debconffilter dies.
+                signal.signal(signal.SIGPIPE, signal.SIG_DFL)
 
             ret = subprocess.call(self.command, preexec_fn=subprocess_setup)
             if ret != 0: