[CI Problem] Failure to import requests, caffe in ci_arm, ci_cpu

[ashutosh-arm]

The issue being reported was seen on local machine with latest docker images. It is not visible in CI yet as the docker hub images are little old. PR #12663 introduced virtual environments where python and its dependencies are installed. Some of the linting issues were fixed here: #12775. However, some tests fail due to error while importing some packages.

1. import requests fails to import this module. It affects many test suites as the below search result suggests.

 ./3rdparty/vta-hw/apps/deploy/python_deploy.py:25:import requests
./ci/scripts/github_skipped_tests_comment.py:27:import requests
./python/tvm/contrib/download.py:58:            import requests
./tests/micro/arduino/test_utils.py:20:import requests
./tests/micro/zephyr/test_utils.py:30:import requests
./vta/tutorials/frontend/deploy_classification.py:43:import argparse, json, os, requests, sys, time

2. import caffe fails to load caffe. The reason being caffe installer still creates soft link outside of virtual env.

   tvm/docker/install/ubuntu_install_caffe.sh

   Line 63 in e5adb83

   ln -s ${PYCAFFE_ROOT}/caffe /usr/local/lib/python3.7/dist-packages/caffe

   . It affects all the caffe tests in TVM.

@leandron @areusch @driazati

[ashutosh-arm]

Raised the PR to fix import issues: #12813