For awhile we've supported automatic detection
guessing if the webserver
supports PATH_INFO and if so automatically using /index.php/$1 for the
article path. I believe this even predates our better REQUEST_URI handling.
I'm considering the idea of dropping support for this automatic setup.
[..]
I don't really like the idea of dropping it, unless our detection of
it not working really does suck. Moving servers is going to break
things no
matter what. This is especially true now that $wgServer is set
explicitly instead of auto-detected.
If we're worried about auto-detection failing, we could do better
auto-detection in the install script ( Make an ajax request to some
script /mw-config/path_info.php/test and see if it can properly
extract the path info).
-bawolff