Fix swift-dispersion-report when partitions overlap

swift-dispersion-report tries to avoid checking a partition more than
once, so it keeps track of partitions already queried and skips
duplicates.

swift-dispersion-report also keeps track of the number of successful
responses; it counts the number of expected replicas to find, and also
counts the number of replicas actually found, and tells the operator
if the numbers differ.

However, in the case that a partition was duplicated, the
expected-responses counter was incremented, but the actual check was
skipped, so it looked as though some copies were missing. Now we only
increment the expected-responses counter if we're actually going to
perform the check.

Change-Id: I22ac2b8066b62ca7c8ebf099c9f602118bb1a298
Merge "Fix swift-dispersion-report when partitions overlap"