Mirror source already removed

Hi all,

I start to play with svk (what an incredible tool !) and I'm very
happy with it. I played with few branches of an existing repository,
tried star merge, sync with multiple repositories.

But today I try to mirror a full repository and after a while I obtain
a mysterious  message:  "Mirror source already removed".

Even If I understand all words of the sentence I don't understand what
does that mean.

I've done:
$> svk depotmap --init
$> svk mirror https://my.server.com/svn/project //mirror/project
$> svk sync //mirror/project
Syncing  https://my.server.com/svn/project
Retrieving log information from 1 to 721
Committed revision 2 from revision 1.
....
Committed revision 133 from revision 132.
Committed revision 134 from revision 133.
Mirror source already removed.

$> svk sync //mirror/project
Syncing  https://my.server.com/svn/project
Retrieving log information from 134 to 721
Mirror source already removed.

Note: Obviously https://my.server.com is up and svn/project reachable !

Any idea of what happen ?

Regards,
Manuel