HFX-1078: [SCTX-1635] Handle storage exception while unplugging VBD.

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>
CA-129089: Disable global login via slave hosts

Signed-off-by: Zheng Li <dev@zheng.li>
Merge pull request #1677 from zli/xenserver/trunk-ring3/CA-129089

CA-129089: Disable global login via slave hosts
Merge pull request #1675 from yunleid/CA-124981

CA-124981: Port the fix of HFX-1078 from clearwater-sp1-lcm to trunk