INFO gives wrong location for loaded config file

[JPBergsma]

When no valid config file is present in home/[username]/.optimade.json you sometimes still get the message:
INFO: [optimade] Using: Mock MongoDB (mongomock)
WARNING: [optimade] Invalid config file or no config file provided, running server with default settings. Errors: ['/home/[username]/Optimade/optimade-python-tools/optimade/server/config.py:126: UserWarning: Unable to find config file at /home/[username]/.optimade.json, using the default settings instead.\n']
INFO: [optimade] Loaded settings from /home/[username]/.optimade.json.