Issue was with datablocks which names would include '/', new filebrowser filelisting code
would cleanup the entire filepath, hence giving invalid filename in this case.
That 'path separator in ID names' bit us already in lib/datatype/datablock separating func,
this is really stupid to allow that in something handled as a filepath imho, but well...
Note: would have break the same under *nix with '\' char.
da6578e647