"get and touch" operations are not counted in server metrics

"get and touch" operations do not increment the cmd_get metric as expected. Here's how to reproduce using the python client. Assuming that cb is a couchbase.bucket.Bucket object:

# insert a test key

cb.upsert('key', 'value')

# fetch it. cmd_get is incremented as expected

cb.get('key')

# fetch it and update the ttl ("get and touch"). cmd_get is not updated

cb.get('key', ttl=99999)

It is helpful to do this while connected to an idle bucket and watching the stats roll by in the web ui. It makes it very apparent that cmd_get is only being counted in the first case (no ttl specified)

I have a client that does exclusively "get and touch" operations and so this bug renders our server-side metrics meaningless.

We first observed this in 3.0.1 community and have reproduced it on 4.6.1 enterprise edition so it has likely existed for a very long time.