If load.php cannot connect to db, it returns the same html page as index.php does, and has a status code of 200.
I think the more expected behaviour would be to return the status 500 (probably should do that for index.php too) and just have a comment /* Could not connect to db */ instead of outputting html (although if outputting a 500 error code, returning html isn't as bad).
Discovered on [[mw:Thread:Project:Support desk/Edit toolbar is not there. Broken]]
See Also:
T37305: Borked API response has HTML DB error appended in case of database lock timeout