Ensure installed directories are not world-writable to avoid Bundler warnings

bin/ruby-build

@@ -44,6 +44,7 @@ install_package() {
   cd "$package_name"
   build_package "$package_name" $*
   after_install_package "$package_name"
+  fix_directory_permissions
   cd "$cwd"
 
   echo "Installed ${package_name} to ${PREFIX_PATH}" >&2
@@ -114,6 +115,11 @@ after_install_package() {
   local stub=1
 }
 
+fix_directory_permissions() {
+  # Ensure installed directories are not world-writable to avoid Bundler warnings
+  find "$PREFIX_PATH" -type d -exec chmod go-w {} \;
+}
+
 use_gcc42_on_lion() {
   if [ "$(uname -s)" = "Darwin" ]; then
     if [ "$(expr "$(sw_vers -productVersion | cut -f 2 -d .)" \>= 7 || true)" -eq 1 ]; then