def METHOD_NAME(self):
    """Peek in requirements.txt to determine if we can assemble from only env files
    If there are any local references, e.g. `-e .`,
    stage the whole repo prior to installation.
    """
    if not os.path.exists("binder") and os.path.exists("setup.py"):
        # can't install from subset if we're using setup.py
        return False
    for name in ("requirements.txt", "requirements3.txt"):
        requirements_txt = self.binder_path(name)
        if not os.path.exists(requirements_txt):
            continue
        with open_guess_encoding(requirements_txt) as f:
            for line in f:
                if is_local_pip_requirement(line):
                    return False
    # didn't find any local references,
    # allow assembly from subset
    return True