Debug information from libcalendaring ends up in the IMAP communication.
Possible solutions are:
- patch libcalendaring to not have any debugoutput
- recompile libcalendaring with QT_NO_DEBUG_OUTPUT QT_NO_WARNING_OUTPUT
- patch libkolab or the calling application to install a custom QtMsgHandler
- catch this in wallace and Roundcube
Because only a messagehandler makes sure that no debug output makes it to stderr and is thus captured by when piping something through a command line utitlity
such as kolab-format, the best solution is to install a custom message handler in libkolab (nothing uses libcalendaring without libkolab).