Currently, the resources associated with the io.Reader returned by
TarStream are only freed when it is read until EOF. This means that
partial uploads or exports (for example, in the case of a full disk or
severed connection) can leak a goroutine and open file. This commit
changes TarStream to return an io.ReadCloser. Resources are freed when
Close is called.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Brian Goff