The version in trusty-proposed looks like it fixes the issue.
ubuntu@ubuntu:~$ apt-cache show pptpd | grep Version
Version: 1.3.4+27+gddb30f8-1ubuntu1
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd start
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd status
* /usr/sbin/pptpd is not running
ubuntu@ubuntu:~$ apt-cache show pptpd | grep Version
Version: 1.3.4+27+gddb30f8-1ubuntu1.1
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd start
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd status
* pptpd is running
The version in trusty-proposed looks like it fixes the issue.
ubuntu@ubuntu:~$ apt-cache show pptpd | grep Version gddb30f8- 1ubuntu1
Version: 1.3.4+27+
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd start
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd status
* /usr/sbin/pptpd is not running
ubuntu@ubuntu:~$ apt-cache show pptpd | grep Version gddb30f8- 1ubuntu1. 1
Version: 1.3.4+27+
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd start
ubuntu@ubuntu:~$ sudo /etc/init.d/pptpd status
* pptpd is running