The svn backend now supports excluding files through a

filterdiff-esque method: SVNClient._filter_diff. This

method looks through the output of svn diff for lines

that begin with Index: that mark the beginning of a

new file in the diff. If the file matches any given

patterns, it will not yield the lines corresponding to

that file's diff.

Ran rbt diff -X ... in an SVN repository and successfully

excluded files and empty files.