The installer does not properly check for a headered ROM, and will patch a headered ROM as though it were unheadered.

[Dylan Morrison]

The installer's routines for ROM checking actually have variables available for checking for a headered ROM, but stupidly I forgot to use them. This should be an easy enough fix.

[Dylan Morrison]

Fixed in commit d416288, the installer now checks for and properly removes the header of headered ROMs during the install.