Merge pull request #737 from untitaker/sprint-branch

Fix some literals
Response data is bytes
Use assert_true instead of assert_

assert_ is deprecated which causes annoying warnings
Use assert_equal instead of assertEquals

assertEquals is deprecated and its use inconsistent
Add missing msg argument to assert_true()
Use assert_in where appropriate
Use assert_false where appropriate
Fix leak in leak detection code

If ensure_clean_request_context found a leak, it would raise an
AssertionError and not clean up the leak, and therefore affect other
testcases.