diff -uNr apr-1.4.5.orig/build/apr_common.m4 apr-1.4.5/build/apr_common.m4
--- apr-1.4.5.orig/build/apr_common.m4	2011-11-21 19:58:38.341263862 +0100
+++ apr-1.4.5/build/apr_common.m4	2011-11-21 20:07:28.368394177 +0100
@@ -202,14 +202,18 @@
 dnl for a user to override configure when it does something stupid.
 dnl
 AC_DEFUN([APR_RESTORE_THE_ENVIRONMENT], [
-if test "x$apr_ste_save_$1" = "x"; then
+dnl Check whether $apr_ste_save_$1 is empty or
+dnl only whitespace. The verbatim "X" is token number 1,
+dnl the following whitespace will be ignored.
+set X $apr_ste_save_$1
+if test ${#} -eq 1; then
   $2$1="$$1"
   $1=
 else
   if test "x$apr_ste_save_$1" = "x$$1"; then
     $2$1=
   else
-    $2$1=`echo $$1 | sed -e "s%${apr_ste_save_$1}%%"`
+    $2$1=`echo "$$1" | sed -e "s%${apr_ste_save_$1}%%"`
     $1="$apr_ste_save_$1"
   fi
 fi