Run this script, see how at the end it prints out the diff for r1, instead of
the diff for r2 as requested. Now that's some serious badness.
#!/bin/sh
rm -rf repos wc
SVN=svn
SVNADMIN=svnadmin
SVNLOOK=svnlook
${SVNADMIN} create repos
mkdir import-tree
echo "This is foo.txt." > import-tree/foo.txt
${SVN} import -m "Import." import-tree file://`pwd`/repos
${SVN} co file://`pwd`/repos wc
echo "First modification to foo.txt, in r2." >> wc/foo.txt
${SVN} ci -m "Commit r2." wc
echo "Next modification to foo.txt, in r3." >> wc/foo.txt
${SVN} ci -m "Commit r3." wc
${SVNLOOK} diff -r1:2 repos
Blocker