Merge pull request #964 from fjf2002/patch-1

prep for possible `set -u` in docker-entrypoint.sh

Author: tianon

Diff for: 10/alpine/docker-entrypoint.sh

@@ -45,7 +45,7 @@ docker_create_db_directories() {
 	chmod 775 /var/run/postgresql || :
 
 	# Create the transaction log directory before initdb is run so the directory is owned by the correct user
-	if [ -n "$POSTGRES_INITDB_WALDIR" ]; then
+	if [ -n "${POSTGRES_INITDB_WALDIR:-}" ]; then
 		mkdir -p "$POSTGRES_INITDB_WALDIR"
 		if [ "$user" = '0' ]; then
 			find "$POSTGRES_INITDB_WALDIR" \! -user postgres -exec chown postgres '{}' +
@@ -84,7 +84,7 @@ docker_init_database_dir() {
 		done
 	fi
 
-	if [ -n "$POSTGRES_INITDB_WALDIR" ]; then
+	if [ -n "${POSTGRES_INITDB_WALDIR:-}" ]; then
 		set -- --waldir "$POSTGRES_INITDB_WALDIR" "$@"
 	fi