implements #636, lazy loading of history and authors to speed up page responsiveness. - loading full history is not always needed, and it's very heavy operation. Now this is lazy loaded when clicking on button
"""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')