Tomcat7 logrotate:superx\u default\u xml.log.gz已存在

每天我都从我的cron收到一封包含以下错误消息的邮件：

/etc/cron.daily/tomcat7:
gzip: /var/log/tomcat7/superx_default_xml.log.gz already exists;    not overwritten
gzip: /var/log/tomcat7/superx.log.gz already exists;    not overwritten
gzip: /var/log/tomcat7/superx-dbforms.log.gz already exists;    not overwritten
gzip: /var/log/tomcat7/saiku.log.gz already exists; not overwritten
gzip: /var/log/tomcat7/superx_default.log.gz already exists;    not overwritten

我已经在Ubuntu14.04上安装了Tomcat7，我甚至没有在logrotate confs上设置任何东西。我尝试设置以下内容，但错误仍然存在：

/var/log/tomcat7/superx.log {
  copytruncate
  weekly
  rotate 52
  compress
  nomail
  missingok
  create 640 tomcat7 adm
}
/var/log/tomcat7/superx-dbforms.log {
  copytruncate
  weekly
  rotate 52
  compress
  nomail
  missingok
  create 640 tomcat7 adm
}
/var/log/tomcat7/saiku.log {
  copytruncate
  weekly
  rotate 52
  compress
  nomail
  missingok
  create 640 tomcat7 adm
}