OK, "find ... -print0 | xargs -0 ..." wasn't portable. This is.

testsuite/merge.test

@@ -43,7 +43,7 @@ cp -p "$from2dir"/sub1/uno "$from3dir"/sub1/dos "$from2dir"/sub1/tres "$chkdir"/
 cp -p "$from3dir"/sub2/subby "$chkdir"/sub2
 
 # Get rid of any directory-time differences
-find "$from1dir" "$from2dir" "$from3dir" "$chkdir" -type d -print0 | xargs -0 touch
+touch "$fromdir"? "$chkdir" "$fromdir"?/sub? "$chkdir"/sub?
 
 checkit "$RSYNC -aHvv \"$fromdir\"?/ \"$todir/\"" "$chkdir" "$todir"