Call button next to contacts in contact list seems unreliable

[459below]

Maybe this is related to https://github.com/jitsi/jitsi/issues/111

The button appears and disappears next to contacts randomly. Whether the contact is using capable to call (i.e. using Jitsi) or not. The button is shown on the chat activity, so this just irritating and doesn't get in the way of Jitsi calls.