Oslo sync to recover from db2 server disconnects
Oslo sync to recover from db2 server disconnects

A checkout listener can be added to sqlalchemy to be able to
handle database disconnect pessimistically and avoid an error in
the event of a DB restart or simply a temp connection issue due
to network glitches. At the moment only mysql is enabled with
this feature. This patch enables db2 as well.

Oslo version in change I5563360b43c4b648f5b035099b0e1d2e71d32503

Partial-Bug: #1231657
Change-Id: I218ef9836f2e0f135897007d2e53354eb1248422

kfwang/Glance-OVA-OVF,paramite/glance,JioCloud/glance,jumpstarter-io/glance,paramite/glance,scripnichenko/glance,stevelle/glance,akash1808/glance,openstack/glance,scripnichenko/glance,akash1808/glance,tanglei528/glance,darren-wang/gl,wkoathp/glance,dims/glance,redhat-openstack/glance,vuntz/glance,stevelle/glance,takeshineshiro/glance,sigmavirus24/glance,ozamiatin/glance,JioCloud/glance,sigmavirus24/glance,ozamiatin/glance,saeki-masaki/glance,klmitch/glance,openstack/glance,redhat-openstack/glance,wkoathp/glance,kfwang/Glance-OVA-OVF,klmitch/glance,rajalokan/glance,rajalokan/glance,tanglei528/glance,saeki-masaki/glance,darren-wang/gl,jumpstarter-io/glance,takeshineshiro/glance,dims/glance,openstack/glance,vuntz/glance