Not possible to edit VPN connection

Editing a VPN PPTP connection does not seam to have any effect. I only tested with PPTP connections.

Try:
1. Create a connection, name it "test"
2. Save the connection
3. Examine the file in /etc/NetworkManager/system-connections
4. Edit the connection, rename it to "renamed" and change some settings
5. Save the connection
6. Verify the configuration file in /etc/NetworkManager/system-connections is still named "test" and the configuration in the config file has not changed.

The interface however still shows the changed values and the new name of the connection. Connecting to the VPN does not work.

I am using Ubuntu 15.04 and:
root@michael2015:/etc/NetworkManager/system-connections# apt-cache policy network-manager
network-manager:
  Installed: 0.9.10.0-4ubuntu15.1
  Candidate: 0.9.10.0-4ubuntu15.1
  Version table:
 *** 0.9.10.0-4ubuntu15.1 0
        500 http://nl.archive.ubuntu.com/ubuntu/ vivid-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ vivid-security/main amd64 Packages
        100 /var/lib/dpkg/status
     0.9.10.0-4ubuntu15 0
        500 http://nl.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages