[Azure Pipelines] Consistently use the "Use Python Version" task (#21722

)

https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/tool/use-python-version?view=azure-devops

The default python/pip on the macOS VMs don't work any longer. It may be
possible to fix this, but to fix the urgent issue use the method
that's supported by Azure Pipelines.

The python version will remain unchanged at 2.7.17, but pip will
change from 19.3.1 to 20.0.2.

pip_install.yml can be simplified because the remaining code path is
the same for macOS and Windows.

Fixes #21691.

.azure-pipelines.yml

@@ -34,6 +34,9 @@ jobs:
  pool:
  vmImage: 'macOS-10.14'
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/affected_tests.yml
  parameters:
  artifactName: 'safari-preview-affected-tests'
@@ -48,6 +51,9 @@ jobs:
  pool:
  vmImage: 'macOS-10.14'
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/affected_tests.yml
  parameters:
  checkoutCommit: 'HEAD^1'
@@ -82,6 +88,9 @@ jobs:
  pool:
  vmImage: 'macOS-10.14'
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/checkout.yml
  - template: tools/ci/azure/pip_install.yml
  parameters:
@@ -114,6 +123,9 @@ jobs:
  variables:
  HYPOTHESIS_PROFILE: ci
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/checkout.yml
  - template: tools/ci/azure/tox_pytest.yml
  parameters:
@@ -161,6 +173,9 @@ jobs:
  variables:
  HYPOTHESIS_PROFILE: ci
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/checkout.yml
  - template: tools/ci/azure/tox_pytest.yml
  parameters:
@@ -209,6 +224,9 @@ jobs:
  HYPOTHESIS_PROFILE: ci
  steps:
  # full checkout required
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/install_chrome.yml
  - template: tools/ci/azure/install_firefox.yml
  - template: tools/ci/azure/update_hosts.yml
@@ -594,6 +612,9 @@ jobs:
  pool:
  vmImage: 'macOS-10.14'
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/checkout.yml
  - template: tools/ci/azure/pip_install.yml
  parameters:
@@ -628,6 +649,9 @@ jobs:
  pool:
  vmImage: 'macOS-10.14'
  steps:
+ - task: UsePythonVersion@0
+ inputs:
+ versionSpec: '2.7.x'
  - template: tools/ci/azure/checkout.yml
  - template: tools/ci/azure/pip_install.yml
  parameters:

tools/ci/azure/pip_install.yml

@@ -2,18 +2,5 @@ parameters:
  packages: ''
 
 steps:
-- script: |
- if [ `which pip` = '/usr/bin/pip' ]; then
- # `sudo pip install` is not used because some packages (e.g. tox) depend on
- # system packages (e.g. setuptools) which cannot be upgraded due to System
- # Integrity Protection, see https://stackoverflow.com/a/33004920.
- pip install --user ${{ parameters.packages }}
- echo "##vso[task.prependpath]$HOME/Library/Python/2.7/bin"
- else
- pip --disable-pip-version-check install --upgrade ${{ parameters.packages }}
- fi
- displayName: 'Install Python packages (macOS)'
- condition: and(succeeded(), eq(variables['Agent.OS'], 'Darwin'))
 - script: pip --disable-pip-version-check install --upgrade ${{ parameters.packages }}
- displayName: 'Install Python packages (Windows)'
- condition: and(succeeded(), eq(variables['Agent.OS'], 'Windows_NT'))
+ displayName: 'Install Python packages'