Fixed warning of test of in_object_space by the reinitialized constant

Signed-off-by: Tsuyoshi Ozawa <ozawa.tsuyoshi@gmail.com>
Merge pull request #162 from oza/fix-in_object_space-test-warning

Fixed warning of test of in_object_space by the reinitialized constant
Modify .travis.yml to test v11 branch
Merge pull request #172 from makimoto/fix-travis-yml-for-v11

Modify .travis.yml to test v11 branch