plug-ins cannot use filefilter to build lists of files

The core problem is that in patch mode, CHANGED_FILES is based upon the patch file without any extra processing. All files that are touched in some way are sent to filefilter in order to trigger the appropriate tests. The problem comes in that files that are added may also be excluded in the same patch. The software won't be able to update CHANGED_FILES until the patch is applied fully applied. At that point, any 'local' file list copy will be incorrect.

Plug-ins that absolutely, positively must keep track of files here must ALSO filter their list against EXCLUDE_PATHS. But realistically, it would better if no such file list was kept and only used CHANGED_FILES directly.