patch-* files are not cumulative - they are against the last release.

For incremental patches, get the pre?-pre?.gz (when available).

To patch up to the actual release, get the *-final.gz.

*** Note: all of the patches from 0.50.0 are _large_ this time around,
    since the models subdirectory got renamed to drivers.  This means
    that every driver is effectively included twice.