Prepare for v2.1.6 release.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.1' into 2.2
Update changelog.

Signed-off-by: crynobone <crynobone@gmail.com>
Update testcase.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.2'