I tried the vendor branching method described in VuFind wiki, but didnt quite manage to accomplish on my task. :)
I pretty much know the basic use of svn (add, commit, checkout and update), but somehow I manage to mess things up with branching and copy. I usually end up in a situation where I get strange errors like "this is not a working copy" or "cannot copy ." etc.
Could you add a command-line examples to your wiki-page, to show exactly how you branch your distributions?
Since this question comes up from time to time, I have added some notes to the wiki:
Please take a look and let me know if you have questions. Also be aware that we’re hoping to gradually make it easier to extend the VuFind code without introducing lots of merge conflicts. Stay tuned on this list (and, if timing permits, the developers call - http://vufind.org/wiki/developers_call) for further discussion of this in the coming months.