environment/lib/python2.7/site-packages/nose/importer.py
def add_path(path, config=None):
    """Ensure that the path, or the root of the current package (if
    path is in a package), is in sys.path.
    """

    # FIXME add any src-looking dirs seen too... need to get config for that
    
    log.debug('Add path %s' % path)    
    if not path:
        return []
    added = []
    parent = os.path.dirname(path)
    if (parent
        and os.path.exists(os.path.join(path, '__init__.py'))):
        added.extend(add_path(parent, config))
    elif not path in sys.path:
        log.debug("insert %s into sys.path", path)
        sys.path.insert(0, path)
        added.append(path)
    if config and config.srcDirs:
        for dirname in config.srcDirs:
            dirpath = os.path.join(path, dirname)
            if os.path.isdir(dirpath):
                sys.path.insert(0, dirpath)
                added.append(dirpath)
    return added
def add_path(path, config=None):
    """Ensure that the path, or the root of the current package (if
    path is in a package), is in sys.path.
    """

    # FIXME add any src-looking dirs seen too... need to get config for that
    
    log.debug('Add path %s' % path)    
    if not path:
        return []
    added = []
    parent = os.path.dirname(path)
    if (parent
        and os.path.exists(os.path.join(path, '__init__.py'))):
        added.extend(add_path(parent, config))
    elif not path in sys.path:
        log.debug("insert %s into sys.path", path)
        sys.path.insert(0, path)
        added.append(path)
    if config and config.srcDirs:
        for dirname in config.srcDirs:
            dirpath = os.path.join(path, dirname)
            if os.path.isdir(dirpath):
                sys.path.insert(0, dirpath)
                added.append(dirpath)
    return added
Ensure that the path, or the root of the current package (if
    path is in a package), is in sys.path.