Code review comment for lp:~alan-griffiths/mir/fix-1284597

The proposed solution depends on knowledge of how things work internally (e.g. that buffers are allocated lazily). I think that something in the spirit of http://paste.ubuntu.com/6998792/ is cleaner (for a more robust solution we need to restore the previous context instead of just releasing the current one, or alternatively, not bind a new context at all if there is an active context already).

Note: I have tried it only on desktop, not N4, so there may be further complications.

A weak needs fixing... I prefer this solution over the proposed, and I think it's the Right Way (TM), but I can live with what is proposed (it's certainly more explicit than what we have now).