Transforming a directory into an SVN repository

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http://serverfault.com – There is a directory (call it A/) with many files, both source and binary. There is an another directory (call it B/) such that A/ contains all files from B/ but in A/ there are many (binary) files not present in B/. I create a new SVN repository from the content of B (svn import). Now I need to make A/ also an SVN repository in order to be able to pull new versions. Transforming A/ into a repository we must not delete the binary files (mentioned above). How to do this? (HowTos)