Don't restart a call if one already in progress
Don't restart a call if one already in progress

Fixes the crash when calling someone while being already in a call
with the same contact.

https://bugzilla.gnome.org/show_bug.cgi?id=671931

GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets