Code review comment for lp:~openstack-gd/nova/lp783478

Generally agree w/ Brian that single-letter vars are bad form; though, to me at least, it seems like there is a lazy-consensus in the Python community that the following cases are acceptable:

 * Exception handlers (except Exception as `e`)
 * List/Generator comprehensions (e.g. [h.name for h in hosts])
 * Index variables (`i` and `j`)

Since pylint doesn't seem to be smart enough to distinguish between these cases, I'd vote we disable that rule and continue our current process of keeping it the reviewer's call.

It'd be a shame if pylint led to *less* idiomatic code.