Check for symlink on index.php should be a warning
The Install Tool / Environment Check for index.php should be a warning not an error.
There are hosting companies outside which allow symlinks only on directories but not on files.
So this error message is misleading:
Path /index.php is not a link The target /index.php should be a link, but is of type file. This can not be fixed. Please investigate.
Please make it a warning instead.