diff -ru ../orig/src/m4/double-slash-root.m4 ../src/m4/double-slash-root.m4
--- ../orig/src/m4/double-slash-root.m4	Mon Jul  3 02:32:46 2006
+++ ../src/m4/double-slash-root.m4	Mon Dec 18 07:48:18 2006
@@ -11,12 +11,12 @@
     [ if test x"$cross_compiling" = xyes ; then
 	# When cross-compiling, there is no way to tell whether // is special
 	# short of a list of hosts.  However, the only known hosts to date
-	# that have a distinct // are Apollo DomainOS (too old to port to)
-	# and Cygwin.  If anyone knows of another system for which // has
+	# that have a distinct // are Apollo DomainOS (too old to port to),
+	# Cygwin, and z/OS.  If anyone knows of another system for which // has
 	# special semantics and is distinct from /, please report it to
 	# <address@hidden>.
 	case $host in
-	  *-cygwin)
+	  *-cygwin | i370-ibm-openedition)
 	    ac_cv_double_slash_root=yes ;;
 	  *)
 	    # Be optimistic and assume that / and // are the same when we
@@ -25,7 +25,7 @@
 	esac
       else
 	set x `ls -di / //`
-	if test $[2] = $[4]; then
+	if test $[2] = $[4] && wc //dev/null >/dev/null 2>&1; then
 	  ac_cv_double_slash_root=no
 	else
 	  ac_cv_double_slash_root=yes