propellor 2.15.4 released with [[!toggle text="these changes"]]
[[!toggleable text="""
   * Build /usr/src/propellor/propellor.git reproducibly,
     which makes the whole Debian package build reproducibly.
     Thanks, Sean Whitton.
   * Obnam: To cause old generations to be forgotten, keepParam can be
     passed to a backup property; this causes obnam forget to be run.
   * Delete /etc/apt/apt.conf.d/50unattended-upgrades.ucf-dist when
     unattended-upgrades is installed, to work around #812380 which results
     in many warnings from apt, including in cron mails.
   * Added Propellor.Property.LetsEncrypt
   * Apache.httpsVirtualHost: New property, setting up a https vhost
     with the certificate automatically obtained using letsencrypt.
   * Allow using combineProperties and propertyList with lists of
     RevertableProperty."""]]