Assertion fail in svn merge 1.9.4

[Nick]

Hi

The following should be invalid IIRC, but rather than give a helpful 
error, it core dumped. This is with 1.9.4 on Linux.

svn merge ^/trunk/web/file.js  ^/branches/X/web/file.js 
^/branches/Y/web/file.js --dry-run

svn: E235000: In file 'subversion/libsvn_subr/dirent_uri.c' line 1595: 
assertion failed (! svn_path_is_url(relative))
Aborted (core dumped)

Nick