pip wheel/install with non-writable cache fails despite warning the cache has been disabled #7488
Description
Coming from #7484
Environment
- pip version: 19.3
- Python version: 3.7 (probably irrelevant)
- OS: linux (probably irrelevant)
Description
Running pip install and pip wheel with a non-writable cache directory leads to an install error, despite pip warning that the cache is disabled due to a permission or ownership issue.
Expected behavior
Installation or build should succeed with a warning that the cache is disabled.
How to Reproduce: pip install
$ mkdir cache
$ chmod -r cache
$ pip install wrapt --cache-dir=cacheOutput
WARNING: The directory '/tmp/brol/cache/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
WARNING: The directory 'cache' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
ERROR: Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: 'cache/wheels/d7/de/2e/efa132238792efb6459a96e85916ef8597fcb3d2ae51590dfd'
Consider using the `--user` option or check the permissions.
pip wheel behaves similarly.
Analysis
For pip install the wheel cache is created before testing the cache is writable.
pip/src/pip/_internal/commands/install.py
Lines 331 to 342 in 81805a5
For pip wheel, no such cache writability check is done.