This is a fix for the following situation (gh-1188):
List() grabs a semaphore token upon entry, starts a goroutine, and
does not release the token until the routine exits (via a defer).
The goroutine iterates over the results from ListCurrentObjects(),
sending them one at a time to a channel, where they are ultimately
processed by be.Load().
Since be.Load() also needs a token, this will result in deadlock if
b2.connections=1.
This fix changes List() so that the token is only held during the call
to ListCurrentObjects().
- be explicit when discarding returned errors from .Close(), etc.
- remove named return values from funcs when naked return not used
- fix some "err" shadowing when redeclaration not needed
