one followup fix for the previous commit.

Author: agentzh

util/build.sh

@@ -8,24 +8,30 @@ home=~
 force=$2
 
 ngx_redis_version=0.3.7
+cd $home/work/nginx/ || exit 1
 ngx_redis_path=$home/work/nginx/ngx_http_redis-$ngx_redis_version
+rm -rf $ngx_redis_path || exit 1
+tar -xzvf ngx_http_redis-$ngx_redis_version.tar.gz || exit 1
 
 cd $ngx_redis_path || exit 1
+
 patch_file=$root/../openresty/patches/ngx_http_redis-$ngx_redis_version-variables_in_redis_pass.patch
 if [ ! -f $patch_file ]; then
     echo "$patch_file: No such file" > /dev/stderr
     exit 1
 fi
 # we ignore any errors here since the target directory might have already been patched.
-patch --forward -p1 < $patch_file
+patch -p1 < $patch_file || exit 1
+
+cd $ngx_redis_path || exit 1
 
 patch_file=$root/../openresty/patches/ngx_http_redis-$ngx_redis_version-default_port_fix.patch
 if [ ! -f $patch_file ]; then
     echo "$patch_file: No such file" > /dev/stderr
     exit 1
 fi
 # we ignore any errors here since the target directory might have already been patched.
-patch --forward -p1 < $patch_file
+patch -p1 < $patch_file || exit 1
 
 cd $root || exit 1