Documentation for 'exclude' says
The paths can be either directories or specific files. If the exclusion
matches a directory, all of its files and subdirectories are ignored.
but I can't see anywhere in the code where it actually affects which
files are ignored, only directories.
It would be really useful to be able to ignore editor backup and
temporary files, e.g. this is taken from Plack::Loader::Restarter:
m![/\\][\._]|\.bak$|^\.?#|~$|_flymake\.p[lm]!;