Serf failures with trunk

I'm getting assert failures while testing serf performance. Typically

../src/subversion/libsvn_ra_serf/update.c:622: (apr_err=235000)
svn: E235000: In file '../src/subversion/libsvn_ra_serf/update.c' line 622: assertion failed (! dir->ref_count)
Aborted

or:

svn: E200014: Checksum mismatch for 'xx/notes/obliterate/fspec-cc1/cc1-dir-ops.svg':
   expected: 0624a5d5bd362105a341d8e5e693238e
     actual: d5e94a461c7a84ff5e41f7ab037dad10

My test setup is:
 - create a repository,
 - import a subversion trunk wc
 - start apache to serve the repository

My test is simply to export or check-out that repository. The exact
error seems to vary from run to run, and occasionally it will run to
completion. I get the error with both BDB and FSFS repositories, with
1.6 and 1.7 mod_dav_svn, on localhost and over a LAN. I don't get the
error with neon.

Can anyone reproduce this?

-- 
Philip