Hi Guix,

I recently added a progress bar for ‘guix copy’:

  https://git.savannah.gnu.org/cgit/guix.git/commit/?id=b03267df6d5ec44e9617b6aab0df14a2e79f822e

However that commit also includes a debugging leftover that breaks
‘send-files’ (in some but not all cases).  Can you spot it?