[DOCKER] Fix: install script regarding get-pip.py during docker build

[brianlan]

Replaced the URL of get-pip.py from

https://bootstrap.pypa.io/get-pip.py

to

https://bootstrap.pypa.io/2.7/get-pip.py

, as the old one doesn't support python 2.7 any more and triggers below error during the building of Dockerfile.demo_android.

ERROR: This script does not work on Python 2.7 The minimum supported Python version is 3.6.

Other than this, the whole docker building procedure works OK.

@leandron Could you please help to review? Thanks.

[leandron]

Looks like a legitimate fix for Python 2.7 setup scripts.

Just would like to check with @tqchen what's the status of our support in general to Python 2.7. Is this something we support in TVM?

[tqchen]

we have dropped the support for python2.7 in the current mainline, so let us consider remove the python2 setup of pip instead. Thank you @brianlan

[brianlan]

we have dropped the support for python2.7 in the current mainline, so let us consider remove the python2 setup of pip instead. Thank you @brianlan

Thanks @leandron, @tqchen. Will remove python2 setup and test again.

[brianlan]

Removed get-pip.py for python2. I rerun the whole docker build process, it works fine. @tqchen

[tqchen]

Thanks @brianlan @leandron !