svn-v4 revids are used for tags on an svn-v3 branch

Latest bzr.dev, bzr-svn 0.5 branch, subvertpy trunk as of ~today.

svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x
svn://svn.lighttpd.net/lighttpd/trunk

The above two branches use svn-v3 revision IDs (except for some normal bzr IDs, and the latest revision being svn-v4), but bzr-svn makes some/most/all of the tags use svn-v4 IDs, meaning "bzr tags" displays their revnos as "?" and they point to nonexistent revisions, making them completely useless. [Woah, run-on sentence.]

I pastebinned an example a week ago: http://paste.pocoo.org/show/BIEg11uNyMGQ4Fr1phem/

The number of svn-v4 IDs has gone up over time. First it was like 15-20%, then like 75%, and now there are only a couple svn-v3 IDs left. I have a habit of deleting and recreating my svn-cache and the repo itself, so maybe it has to do with that?

(I haven't created any clean branches to help debug this. My branches should be clean enough, and I've abused their svn server enough lately... More importantly, it's melting my brain.)