ikiwiki 1.20 released with these changes:

   * Relicense the templates and basewiki under the 2-clause BSD license.
     Since these can easily become part of other people's websites, they
     should be under as permissive a license as possible.
   * Add --syslog config option, to log to the syslog.
   * Catch failing IPC::Open2 in tidy plugin and retry in case this is a
     transient failure to fork (which I've seen happen in the wild).
   * Fix a bug in the aggregator introduced last version that caused all
     aggregator state to be lost during a non-aggregating build.