Zombie outgoing call that can't be hung up

I dialed a number that happened to call me at the exact same moment - I received the call and completed it, but the outgoing call remains in a zombie state, can't be hung up and I can't make any other calls:

$ /usr/share/ofono/scripts/hangup-call /ril_1/voicecall02
$ /usr/share/ofono/scripts/hangup-all
$ /usr/share/ofono/scripts/list-calls
[ /ril_1 ]
    [ /ril_1/voicecall02 ]
        LineIdentification = +48......
        RemoteMultiparty = 0
        RemoteHeld = 0
        State = dialing
        Name =
        Emergency = 0
        Multiparty = 0
[ /ril_0 ]

This bug was reported on a turbo running rc-proposed/127. The phone had a single valid SIM card inserted in the second slot (/ril_1).

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: ofono 1.17.bzr6914+15.04.20160413.1-0ubuntu1 [origin: LP-PPA-ci-train-ppa-service-stable-phone-overlay]
Uname: Linux 3.10.100-user-01769-g42b9fe3 aarch64
ApportVersion: 2.17.2-0ubuntu1.3touch1
Architecture: armhf
Date: Thu Jul 7 19:49:32 2016
InstallationDate: Installed on 2016-07-07 (0 days ago)
InstallationMedia: Ubuntu 15.04 - armhf (20160707-020304)
SourcePackage: ofono
UpgradeStatus: No upgrade log present (probably fresh install)