saluttest.exec_test_deferred: if make_connection fails, die
saluttest.exec_test_deferred: if make_connection fails, die

Adapted from Will's commit 9071c1af4 in Gabble, although that one needs
to cope with multiple connections.

freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut