[Tech] Download CHK without filename

[bbackde at googlemail.com]

I tested with the latest node version. Tried to download a file that
was uploaded with "TargetFilename=" (^=empty), and used key
"CHK at bla/filename.ext" for the download. Surprisingly the node did not
return error code=11 to indicate I should retry the download without a
filename, but the node did download the file.

Is this now transparent for an application and you forget to tell us
about? Should an application still check for errorcode=11 and remove
the filename from a CHK key?