svnsync: Assertion failed: (svn_fspath__is_canonical(child_fspath)), ...

I'm running into a bug in svnsync that was fixed some years ago for svn
http://subversion.tigris.org/issues/show_bug.cgi?id=4088

The FreeBSD project is now running for users subversion mirror without svn:// access.
The main issue I'm running into is a bug because the repos are located on /$repo and not on a sub path like /svn/$repo

Running my existing svnsync repo against the new URL results in a core dump of svnsync

Assertion failed: (svn_fspath__is_canonical(child_fspath)), function svn_fspath__skip_ancestor, file subversion/libsvn_subr/dirent_uri.c, line 2492.
Abort trap (core dumped)

Until now I have to clean after each svnsync the svnsync lock with
$ svn pd svn:sync-lock --revprop -r 0 file:///$repo

Details if from interest:

svn properties (r0):
svn:date : 2012-07-14T06:36:59.701452Z
svn:sync-from-url : https://svn.freebsd.org/ports/
svn:sync-from-uuid : 35697150-7ecd-e111-bb59-0022644237b5
svn:sync-last-merged-rev : 392393

$ svn --version
svn, version 1.8.13 (r1667537)
   compiled Jul 2 2015, 04:04:19 on amd64-portbld-freebsd10.1
...
* ra_svn : Module for accessing a repository using the svn network protocol.
  - handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
  - handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
  - using serf 1.3.8
  - handles 'http' scheme
  - handles 'https' scheme

Should I re- open bug #4088 ?

-- 
Regards,
olli