try_git.py

import subprocess
try:
    tree = subprocess.check_output(["git", "rev-parse", "HEAD"]).strip()
except OSError:
    import warnings
    warnings.warn("Cannot link examples because we cannot retrieve the git version", Warning)
else:
    extlinks = {'example': ('https://github.com/DEAP/deap/blob/{tree}/examples/%s.py'.format(tree=tree), "examples/")}