Comment 5 for bug 340347

A couple of thoughts while writing a test for this:

- Transport.readv() says it will return either a list or a generator, so probably ReadVFile is at fault in insisting that it must get a generator.

- On the other hand, TransportLogDecorator is a debugging aid so it is desirable that as much as possible it should pass data through unchanged. Therefore, if it gets a generator from the underlying transport, it should pass one back out.

Fixing either of these would close the bug but I think perhaps we should do both of them.