concat a path for this name

def addEnvPath(env, name, value):
    """ concat a path for this name """
    try:
        oldval = env[name]
        if not oldval.endswith(';'):
            oldval = oldval + ';'
    except KeyError:
        oldval = ""
    if not value.endswith(';'):
        value = value + ';'
    env[name] = oldval + value