* Support backing up from tasksel if it is run as part of a larger

debconf-using program such as d-i; while tasksel will not enable the
  backup capb itself, if it is enabled and the user chooses to back up, it
  will exit with code 10. Note that this code, rather than 30, was chosen
  to interoperate with d-i, which rather inexplicably uses 10 instead of 30
  to signal backup across process boundries.

debian/changelog

@@ -23,8 +23,14 @@ tasksel (2.38) UNRELEASED; urgency=low
     incremental progress displays being logged to stderr, since eg in d-i that
     results in a lot (possibly many megabytes) of download progress info in
     the logs.
-
- -- Joey Hess <joeyh@debian.org>  Sun, 25 Dec 2005 16:45:55 -0500
+  * Support backing up from tasksel if it is run as part of a larger
+    debconf-using program such as d-i; while tasksel will not enable the
+    backup capb itself, if it is enabled and the user chooses to back up, it
+    will exit with code 10. Note that this code, rather than 30, was chosen
+    to interoperate with d-i, which rather inexplicably uses 10 instead of 30
+    to signal backup across process boundries.
+
+ -- Joey Hess <joeyh@debian.org>  Sun, 25 Dec 2005 17:14:36 -0500
 
 tasksel (2.37) unstable; urgency=low
 

tasksel-debconf

@@ -26,7 +26,7 @@ else
 fi
 
 db_input high $question || true
-db_go || true
+db_go # note: intentionally unguarded
 db_fset $question seen false
 db_get $question
 echo "$RET" >$tmpfile

tasksel.pl

@@ -440,13 +440,19 @@ sub main {
 		my @default = grep { $_->{_display} == 1 && ($_->{_install} == 1 || $_->{_installed} == 1) } @tasks;
 		my $tmpfile=`tempfile`;
 		chomp $tmpfile;
-		system($debconf_helper, $tmpfile,
+		my $ret=system($debconf_helper, $tmpfile,
 			task_to_debconf("shortdesc", @list),
 			task_to_debconf("shortdesctrans", @list),
 			task_to_debconf("shortdesc", @default),
-			$question);
+			$question) >> 8;
+		if ($ret == 30) {
+			exit 10; # back up
+		}
+		elsif ($ret != 0) {
+			error "debconf failed to run";
+		}
 		open(IN, "<$tmpfile");
-		my $ret=<IN>;
+		$ret=<IN>;
 		if (! defined $ret) {
 			die "tasksel canceled\n";
 		}