Azure devops管道缓存python依赖项

我想在requirement.txt中缓存依赖项。看见这是我的azure-pipelines.yml

# Python package
# Create and test a Python package on multiple Python versions.
# Add steps that analyze code, save the dist with the build record, publish to a PyPI-compatible index, and more:
# https://docs.microsoft.com/azure/devops/pipelines/languages/python

trigger:
- master

pool:
  vmImage: 'ubuntu-latest'
strategy:
  matrix:
    Python38:
      python.version: '3.8'

variables:
  PIP_CACHE_DIR: $(Pipeline.Workspace)/.pip

steps:

- task: UsePythonVersion@0
  inputs:
    versionSpec: '$(python.version)'
  displayName: 'Use Python $(python.version)'

- task: Cache@2
  inputs:
    key: 'python | "$(Agent.OS)" | requirements.txt'
    restoreKeys: | 
      python | "$(Agent.OS)"
      python
    path: $(PIP_CACHE_DIR)
  displayName: Cache pip packages

- script: |
    python -m pip install --upgrade pip
    pip install -r requirements.txt
  displayName: 'Install dependencies'

- script: |
    pip install pytest pytest-azurepipelines
    pytest
  displayName: 'pytest'

my requirements.txt中指定的依赖项安装在每个管道运行中

管道任务Cache@2给出以下输出

Starting: Cache pip packages
==============================================================================
Task         : Cache
Description  : Cache files between runs
Version      : 2.0.1
Author       : Microsoft Corporation
Help         : https://aka.ms/pipeline-caching-docs
==============================================================================
Resolving key:
 - python           [string]
 - "Linux"          [string]
 - requirements.txt [file] --> EBB7474E7D5BC202D25969A2E11E0D16251F0C3F3F656F1EE6E2BB7B23868B10
Resolved to: python|"Linux"|jNwyZU113iWcGlReTrxg8kzsyeND5OIrPLaN0I1rRs0=
Resolving restore key:
 - python  [string]
 - "Linux" [string]
Resolved to: python|"Linux"|**
Resolving restore key:
 - python [string]
Resolved to: python|**
ApplicationInsightsTelemetrySender will correlate events with X-TFS-Session 85b76fe3-b469-4330-a584-db569bc45342
Getting a pipeline cache artifact with one of the following fingerprints:
Fingerprint: `python|"Linux"|jNwyZU113iWcGlReTrxg8kzsyeND5OIrPLaN0I1rRs0=`
Fingerprint: `python|"Linux"|**`
Fingerprint: `python|**`
There is a cache miss.
ApplicationInsightsTelemetrySender correlated 1 events with X-TFS-Session 85b76fe3-b469-4330-a584-db569bc45342
Finishing: Cache pip packages

---

启用系统诊断并查看Post job:Cache pip包的日志显示了未创建缓存的原因

##[debug]Evaluating condition for step: 'Cache pip packages'
##[debug]Evaluating: AlwaysNode()
##[debug]Evaluating AlwaysNode:
##[debug]=> True
##[debug]Result: True
Starting: Cache pip packages
==============================================================================
Task         : Cache
Description  : Cache files between runs
Version      : 2.0.1
Author       : Microsoft Corporation
Help         : https://aka.ms/pipeline-caching-docs
==============================================================================
##[debug]Skipping because the job status was not 'Succeeded'.
Finishing: Cache pip packages

构建管道中存在失败的测试。缓存是在我删除失败的测试后使用的