This dir can be used to drop *sed* script as patches (we can not use
patch as its not part of the default install) to fixup stuff that is
problematic during the upgrade (like doc-base and
/usr/sbin/install-docs).

The files have the format _path_to_binary.md5sum  
The upgrader will check for binaries with the matching md5sum and
apply the patches if the md5sum is correct (first --dry-run to 
ensure it applies cleanly).

Caveats:
- it does *not* do binary patching
- the md5sum calculation in python is not efficient, so do
  *not* patch huge files
