尽管已安装future，但是pip仍在尝试收集它。这是一台离线计算机，因此无法自动提取软件包。使用pip3代替python3 -m pip会得到相同的结果。
$ python3 -m pip install ~/future-0.17.1.tar.gz
Processing /home/vader/future-0.17.1.tar.gz
Building wheels for collected packages: future
Running setup.py bdist_wheel for future ... done
Stored in directory: /home/vader/.cache/pip/wheels/c5/09/3a/1433ca68e4b2b77cd517ad0ef03182174a8f2c5fd0a8a89b1f
Successfully built future
Installing collected packages: future
Successfully installed future-0.17.1
$ python3 -m pip install ~/ffmpeg-python-0.1.18.tar.gz
Processing /home/vader/ffmpeg-python-0.1.18.tar.gz
Collecting future (from ffmpeg-python==0.1.18)
Retrying...NewConnectionError...Failed to establish a new connection
我该如何解决？