Speed up of last_changeset extraction in VCS, in edge cases for git we can get 10x speed improvement by limiting the history extraction if we only need last changeset
"""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')