Comment 19 for bug 1778946

Comment 6 and 7 in the upstream GNOME NetworkManager-pptp bug report :
    https://bugzilla.gnome.org/show_bug.cgi?id=785771#c6
are relevant to this bug (but not the 'cp -a' issue).

As mentioned, the following exit in /etc/ppp/ip-up.d/000resolvconf when the interface is managed by NM, seems the right solution.

    case "$6" in
      nm-pptp-service-*|nm-l2tp-service-*|/org/freedesktop/NetworkManager/PPP/*)
        # NetworkManager handles it
        exit 0
        ;;
    esac

Perhaps the exit should be added to /etc/ppp/ip-up.d/0000usepeerdns for instances when resolvconf package isn't installed?