Fix exit status 10 for invalid /etc/localtime symlinks

Signed-off-by: Benjamin Drung <benjamin.drung@canonical.com>

debian/tests/debconf

@@ -79,6 +79,25 @@ class TestDebconf(unittest.TestCase):
             stdout=subprocess.DEVNULL,
         )
 
+    def test_broken_symlink(self) -> None:
+        """Test pointing /etc/localtime to an invalid location."""
+        self._set_timezone(pathlib.Path("/bin/sh"))
+        self._reset_debconf()
+        self._call_dpkg_reconfigure()
+        self.assertEqual(self._get_timezone(), "Etc/UTC")
+        self.assertEqual(self._get_selection(), "Etc/UTC")
+
+    def test_broken_symlink_but_debconf_preseed(self) -> None:
+        """Test broken /etc/localtime but existing debconf answers."""
+        self._set_timezone(pathlib.Path("/bin/sh"))
+        self._call_debconf_set_selections(
+            "tzdata tzdata/Areas select Pacific\n"
+            "tzdata tzdata/Zones/Pacific select Yap\n"
+        )
+        self._call_dpkg_reconfigure()
+        self.assertEqual(self._get_timezone(), "Pacific/Yap")
+        self.assertEqual(self._get_selection(), "Pacific/Yap")
+
     def test_etc_localtime_precedes_debconf_preseed(self) -> None:
         """Test dpkg-reconfigure uses /etc/localtime over preseed."""
         self._set_timezone("Asia/Jerusalem")

debian/tzdata.config

@@ -298,44 +298,38 @@ elif [ -e "$DPKG_ROOT/etc/timezone" ]; then
 fi
 
 TIMEZONE="$(convert_timezone "$TIMEZONE")"
+
 if [ -f "$DPKG_ROOT/usr/share/zoneinfo/$TIMEZONE" ] ; then
 	AREA="${TIMEZONE%%/*}"
 	ZONE="${TIMEZONE#*/}"
-fi
 
-# The timezone is already configured
-if [ -L "$DPKG_ROOT/etc/localtime" ] ; then
 	# Don't ask the user, except if he/she explicitely asked that
 	if [ -z "$DEBCONF_RECONFIGURE" ] ; then
 		db_fset tzdata/Areas seen true
 		db_fset "tzdata/Zones/$AREA" seen true
 	fi
 # The timezone has never been configured or is falsely configured
-elif ! [ -L "$DPKG_ROOT/etc/localtime" ] || [ -n "$DEBCONF_RECONFIGURE" ] ; then
-	if [ -z "$AREA" ] || [ -z "$ZONE" ] ; then
-		RET=""
-		db_fget tzdata/Areas seen || RET=false
-		if [ "$RET" = true ] ; then
-			db_get tzdata/Areas
-			AREA=$RET
-		else
-			AREA="Etc"
-		fi
+else
+	RET=""
+	db_fget tzdata/Areas seen || RET=false
+	if [ "$RET" = true ] ; then
+		db_get tzdata/Areas
+		AREA=$RET
+	else
+		AREA="Etc"
+	fi
 
-		RET=""
-		db_fget "tzdata/Zones/$AREA" seen || RET=false
-		if [ "$RET" = true ] ; then
-			db_get "tzdata/Zones/$AREA"
-			ZONE=$RET
-		else
-			ZONE="UTC"
-		fi
+	RET=""
+	db_fget "tzdata/Zones/$AREA" seen || RET=false
+	if [ "$RET" = true ] ; then
+		db_get "tzdata/Zones/$AREA"
+		ZONE=$RET
+	else
+		ZONE="UTC"
 	fi
+
 	db_fset tzdata/Areas seen false
 	db_fset "tzdata/Zones/$AREA" seen false
-# The user want to handle the timezone by him/herself
-else
-	exit 0
 fi
 
 # Initializes debconf default values from the ones found in