fd.o #25684: fix detection of accounts that already exist
fd.o #25684: fix detection of accounts that already exist

Based on a patch from Jani Monoses <jani@ubuntu.com>.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control