rc: fix unionfs stuck in read-only mode

Pondering whether this is a bug in the actual file system code...

src/etc/rc

@@ -19,15 +19,6 @@ export HOME PATH
 
 PLATFORM=`/bin/cat /usr/local/etc/platform`
 
-if [ -e /root/force_fsck ]; then
-	echo "Forcing filesystem check..."
-	/sbin/fsck -y -t ufs /
-	if [ "$PLATFORM" = "nanobsd" ]; then
-		/sbin/fsck -y -t ufs /cf
-	fi
-	/bin/rm -f /root/force_fsck
-fi
-
 if [ "${PLATFORM}" = "nanobsd" ]; then
 	kldstat -qm zfs
 	if [ $? = 0 ]; then
@@ -121,6 +112,12 @@ else
 	fi
 fi
 
+if [ -d /root/core ]; then
+	# unionfs gets stuck in read-only mode due to early mount
+	/usr/bin/make -C /root/core umount
+	/usr/bin/make -C /root/core mount
+fi
+
 # rewrite message of the day
 /etc/rc.d/motd onestart