Make more portable.

config/prep_buildtree

@@ -3,7 +3,6 @@
 # This script prepares a PostgreSQL build tree.  It is intended
 # to be run by the configure script.
 
-set -e
 me=`basename $0`
 
 help="\
@@ -20,14 +19,16 @@ sourcetree=$1
 
 buildtree=${2:-'.'}
 
-for item in `find "$sourcetree" -type d -\( -name CVS -prune -o -print -\)`; do
-    subdir=`expr "$item" : "$sourcetree\(.*\)"` || true
-    mkdir -p "$buildtree/$subdir"
+for item in `find "$sourcetree" -type d \( -name CVS -prune -o -print \)`; do
+    subdir=`expr "$item" : "$sourcetree\(.*\)"`
+    if test ! -d "$buildtree/$subdir"; then
+        mkdir -p "$buildtree/$subdir" || exit
+    fi
 done
 
 for item in `find "$sourcetree" -name Makefile -o -name GNUmakefile`; do
-    subdir=`expr "$item" : "$sourcetree\(.*\)"` || true
-    if test ! -e "${item}.in"; then
-        ln -fs "$item" "$buildtree/$subdir"
+    subdir=`expr "$item" : "$sourcetree\(.*\)"`
+    if test ! -f "${item}.in"; then
+        ln -fs "$item" "$buildtree/$subdir" || exit
     fi
 done