Adjust unit tests to clarify existing device usage

Most of the unit tests run with check_mount=False, so if a device is
chosen by a test that was not created ahead of time, the test will still
work, since the "tmp" directory creation in DiskFile.create() using
mkdirs(), thereby creating the a directory for the device (perhaps that
should be fixed).

This change refactors the test code to use the exiting device
explicitly.

Change-Id: Ib4fbf069596672bb0b98f41573f312eabde38f98
Make test_close_error run much faster

Change-Id: Iddeab82eed2f781837ab41c9e99e8450bb14a974
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
Make sure SLO's bulk-delete logger is configured

The SLO middleware supports deletion of an object and all its
segments; internally, it uses the same code as the bulk middleware to
do this (swift.common.middleware.bulk.Bulk).

If something goes wrong in the bulk delete, the Bulk object logs the
exception; however, SLO's Bulk object's logger always has the default
logging config, so if you've got a non-default logging setup
(e.g. syslog to a remote log host), this one exception message goes
somewhere else (e.g. local syslog).

This patch makes SLO and its bulk deleter share a logger so all the
messages go to the same place.

Change-Id: Idb01b5640257a02dbb9c698851a14ad8fba11a2d
lower the default yield frequency for bulk requests

closes bug 1270246

DocImpact

Change-Id: If7f484d1a580e991896ac55f822655110266f3fa
Merge "Make sure SLO's bulk-delete logger is configured"
Merge "lower the default yield frequency for bulk requests"
Merge "Fix swift-dispersion-report when partitions overlap"
Merge "Make test_close_error run much faster"
Merge "Adjust unit tests to clarify existing device usage"