Perhaps I'm completely missing something, but...
It seems like ActionView::Helpers::AssetTagHelper#compute_public_path
keeps a cache of all public paths along with the appended asset id.
However, this means that applications (in this case, Facebook) that
cache based on the name of the file will never pull the new file if
it's been modified.
Would it make sense to either:
(a) Not cache the public paths in development mode or
(b) Clear ActionView::Base.computed_public_paths after the application
has been reloaded