tests: replace imported module to avoid check-code.py error This is a part of preparation to apply checking with check-code.py on code fragments embedded in *.t test scripts.

tests: bulk change to avoid "unneeded trailing ',' ..." error of check-code.py This is a part of preparation to apply checking with check-code.py on code fragments embedded in *.t test scripts. "trailing ','" at the end of command option list in the code fragment of test-bundle2-format.t is still left as it is, in order to follow the style of command definitions in Mercurial core.

tests: define class in modern style to avoid check-code.py error This is a part of preparation to apply checking with check-code.py on code fragments embedded in *.t test scripts.