The configuration will locate automatically by default. The location folder is defined on build process by --sysconfdir=/etc.
On runtime the argv[0] isn't set on console with absolute path, so the configuration could not found.
As service the argv[0] serves this information and the program is running.
The actual way to fix this, is to try first argv[0] for absolute path. Otherwise the cwd will fetched by the program.
This is fixed in revision 86.