I can't be sure which version of SVN this occurred with (I believe it was a very recent version), but I had a user email me the other day about a broken revision. After taking a look, it appears that SVN picked the right offset, the right length, and the right checksums, but the wrong revision number. It looks like this was during a tag operation (or a copy from a previous revision). The revision the backend chose didn't even have a related file, and the contents certainly were not the same.
Any ideas where I should look to find the cause of this problem? Also, I noticed that files seem to have both a SHA-1 and a uniquifier, but directories don't. The structure document in libsvn_fs_fs doesn't speak of this difference between files and directories. It just says that newer formats have it while older ones don't. Should directories have both the SHA-1 and unquifier? Thanks! -John
