It was especially bad on our GUI platforms with a frontend that polls it.
No need to log it every few seconds if it's unchanged. Make it slightly
less allocate-y while I'm here.
The test's LocalBackend was not shut down (Shutdown both releases
resources and waits for its various goroutines to end). This should
fix the test race we were seeing. It definitely fixes the file
descriptor leak that preventing -race -count=500 from passing before.
