Transient submission which breaks several tests by refactoring test

Test refactoring moved a check into a private method, and left all
other code the same, yet somehow the change breaks multiple tests in
my development environment.
Revert "Use RevWalk(repo) constructor instead of RevWalk(ObjectReader)"

This reverts commit aa45c1c36b5515132db949c8118544a9c74811b2.

The RevWalk javadoc states that RevWalk will allocate an ObjectReader
internally and it is expected that the caller (us) will free the
ObjectReader.  If we must free it, then there is no point in having
something else allocate it.
Release each JGit ObjectReader opened during JGitAPI operations

The JGit javadoc states that the caller is resposnsible for releasing
the ObjectReader, even if the ObjectReader is silently allocated by
the RevWalk or TreeWalk constructor.