I'm attempting a merge with the SVN plugin via the web interface
with ikiwiki-3.20100403 and subversion 1.6.11.

The web interface says

    Your changes conflict with other changes made to the page.
    
    Conflict markers have been inserted into the page content. Reconcile the conflict and commit again to save your changes.

However there are no merge conflict markers in the page. My apache error log says:

    [Fri Apr 30 16:43:57 2010] [error] [client 10.64.64.42] svn: Commit failed (details follow):, referer: https://unixwiki.ncl.ac.uk/ikiwiki.cgi
    [Fri Apr 30 16:43:57 2010] [error] [client 10.64.64.42] svn: Authorization failed, referer: https://unixwiki.ncl.ac.uk/ikiwiki.cgi

-- [[Jon]]