apiserver/client: work around compiler bug with named return values

[davecheney]

Upstream golang/go#14904

Returning a complex variable by value with a mix of named and implicit
returns was throwing off the compiler. This caused the memory occupied
by the return value to be considered dead before the end of the
function, leading to the gc freeing that memory prematurely.

The bug is not believed to not affect any shipping Go 1.6 compiler, but
it seems prudent to work around the compiler issue in our code.

(Review request: http://reviews.vapour.ws/r/4336/)

[davecheney]

$$JFDI$$

(it's important)

[jujubot]

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju