I want to set an external reference to a relative project path, which does not contain spaces (googling the assertion gave a hint that spaces can be involved into creating this assertion). I can enter the path but once I press the context menu entry "Fetch HEAD revision and adjust to it", I get the assertion with the hint (svn_dirent_is_absolute(local_abspath)). The local path is 'XXX', the referenced project is located at '../../../reference_project/trunk/my_src/XXX' and should exist, as a second parallel project which is setup in similar fashion and directory structure can actually reference the same sub-directory.
My Tortoise svn is TortoiseSVN 1.9.3, Build 27166 - 64 Bit -dev, 2016/02/08 07:58:04 on Windows 7.