fixed issue #671 commenting on pull requests sometimes used old JSON encoder and broke. This changeset replaces it's with RhodeCode json encoder to ensure all data is properly serializable
"""Various utilities to work with Python < 2.7.Those utilities may be deleted once ``vcs`` stops support for older Pythonversions."""importsysifsys.version_info>=(2,7):unittest=__import__('unittest')else:unittest=__import__('unittest2')