/etc/exports and /usr/src are optional

src/etc/mtree/special

@@ -1,4 +1,4 @@
-#	$OpenBSD: special,v 1.17 1997/11/24 08:39:50 deraadt Exp $
+#	$OpenBSD: special,v 1.18 1998/02/18 20:04:44 millert Exp $
 #	$NetBSD: special,v 1.4 1996/05/08 21:30:18 pk Exp $
 #	@(#)special	8.2 (Berkeley) 1/23/94
 #
@@ -26,7 +26,7 @@ daily		type=file mode=0644 uname=root gname=wheel
 daily.local	type=file mode=0644 uname=root gname=wheel optional
 disklabels	type=dir mode=0755 uname=root gname=wheel ignore
 ..	#disklabels
-exports		type=file mode=0644 uname=root gname=wheel
+exports		type=file mode=0644 uname=root gname=wheel optional
 fbtab		type=file mode=0644 uname=root gname=wheel
 fstab		type=file mode=0644 uname=root gname=wheel
 ftpusers	type=file mode=0644 uname=root gname=wheel
@@ -100,7 +100,7 @@ sbin		type=dir mode=0755 uname=root gname=wheel ignore
 ..	#usr/sbin
 share		type=dir mode=0755 uname=root gname=wheel ignore
 ..	#usr/share
-src		type=dir mode=0775 uname=root gname=wsrc ignore
+src		type=dir mode=0775 uname=root gname=wsrc ignore optional
 ..	#usr/src
 ..	#usr