One of the really nice things about dpkg is dpkg-divert. This allows you to specify that a certain file should not be installed in its normal location, but rather should be diverted elsewhere. This can be incredibly handy when you want to override only part of a package, or if you want the original file, just in a different location.
In my case, I need svn to be "diverted" to svn.real, since svn is a script that knows about some local differences in my environment, however it still call svn.real to do the real work.
I am not sure how to mark this as a feature request, but that is what it is, it is not really an "issue" per se.
Can't you just put your svn before the Homebrew svn in the PATH?
Hmm. I was so fixated on the other solution… to answer your question, yes I could, given that I am hardcoding the name svn.real at the moment, I could just as easily hardcode in /usr/local/svn. It does mean that I need to add a new directory to my $PATH, but that is not a huge issue.
I still think that this could be useful functionality, but in my case I can easily work around it. I am happy to close the issue if you do not think that this would be more generally useful.
Also: HOMEBREW_SVN (see man brew)
You can also brew unlink svn and then use $(brew --prefix svn) (or just hardcode /usr/local/opt/bin/svn).
brew unlink svn
$(brew --prefix svn)
Closing because there are already multiple ways to accomplish this.