Yes, it’s possible with svn 1.6. It’s documented in the nightly build version of the svn book. But even though file externals are working, you should only do it with text files (for now) because binary files won’t work correctly as file externals.
It appears that the functionality of the Forest Extension is being implemented into core Mercurial (as of 1.3): https://www.mercurial-scm.org/wiki/Subrepository. Currently marked as “experimental” but perhaps will be the route to handle svn:external -type functionality as of v1.4.
I am the author of the quote in the question, which came from a previous answer. Jason is right to be suspicious of brief statements such as mine, and to ask for an explanation. Of course, if I fully explained everything in that answer, I would need to have written a book. Mike is also … Read more