[sqlalchemy] Samples with last timestamp are excluded from statistics output

[Aleksey Ripinen]

In sqlalchemy backend statistics samples with last timestamp can be excluded from statistic output.
It happened when last period end equals timestamp end. For example: period - 60s, time interval - from "2015-06-09T:16:30:00" to "2015-06-09T:16:31:00", operation to compare - le. In this situation all samples with timestamp "2015-06-09T:16:31:00" are not included in request. But if we use another backend, for example mongo, the same request will work correct.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/189670

[OpenStack Infra (hudson-openstack)]

Change abandoned by gordon chung (<email address hidden>) on branch: master
Review: https://review.openstack.org/189670
Reason: cleanup

[gordon chung (chungg)]

no one worked on ceilometer legacy storage for over a year.