Small style and quoting tweaks

bin/build

@@ -122,27 +122,27 @@ cache_dir="${layers_dir}/shim"
 mkdir -p "${cache_dir}"
 echo "cache = true" >"${layers_dir}/shim.toml"
 
-"${target_dir}/bin/compile" "$app_dir" "${cache_dir}" "${platform_dir}/env"
+"${target_dir}/bin/compile" "${app_dir}" "${cache_dir}" "${platform_dir}/env"
 
 # copy profile.d scripts into a layer so they will be sourced
 if [[ -d .profile.d ]]; then
 	profile_dir="${layers_dir}/profile"
 
 	mkdir -p "${profile_dir}/profile.d"
 	for script in .profile.d/*; do
-		dest="${profile_dir}/profile.d/$(basename "$script")"
+		dest="${profile_dir}/profile.d/$(basename "${script}")"
 
 		# wrap each script and set $HOME to <app dir>
-		cat <<'EOF' >"$dest"
-__cnb_shim__HOME=$HOME
+		cat <<'EOF' >"${dest}"
+__cnb_shim__original_HOME="${HOME}"
 HOME=$(pwd)
 
 EOF
-		cat "$script" >>"$dest"
-		cat <<'EOF' >>"$dest"
+		cat "${script}" >>"${dest}"
+		cat <<'EOF' >>"${dest}"
 
-HOME=$__cnb_shim__HOME
-unset __cnb_shim__HOME
+HOME="${__cnb_shim__original_HOME}"
+unset __cnb_shim__original_HOME
 EOF
 	done
 
@@ -156,4 +156,4 @@ if [[ -f "${target_dir}/export" ]]; then
 fi
 
 # run bin/release, read Procfile, and generate launch.toml
-"${bp_dir}/bin/release" "${target_dir}" "${layers_dir}" "${platform_dir}" "$app_dir"
+"${bp_dir}/bin/release" "${target_dir}" "${layers_dir}" "${platform_dir}" "${app_dir}"