Question about working directory of pip_setup extract

[hisener]

This question is somewhat related to what we changed in pipenv recently in #8136. I have a similar issue with pip_setup manager. I have a setup.py in a subfolder, which has the following code:

with open("README.md") as f:	
    description = f.read()

However, it fails with the No such file or directory: 'README.md error because the working directory is the project root.

So would it make sense to change the cwd to packageFile location in

renovate/lib/manager/pip_setup/extract.ts

Line 47 in b8e9a13

const cwd = config.localDir;

Full error message:

DEBUG: Executing command (repository=PicnicSupermarket/picnic-scratch)
       "command": "docker run --rm --name=renovate_pip --label=renovate_child -v \"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\":\"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\" -v \"/tmp/renovate/cache\":\"/tmp/renovate/cache\" -w \"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\" docker.io/renovate/pip bash -l -c \"python \\\"renovate-pip_setup-extract.py\\\" \\\"python-package-test/setup.py\\\"\""
 WARN: Failed to read setup.py file (repository=PicnicSupermarket/picnic-scratch, packageFile=python-package-test/setup.py)
       "err": {
         "killed": false,
         "code": 1,
         "signal": null,
         "cmd": "docker run --rm --name=renovate_pip --label=renovate_child -v \"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\":\"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\" -v \"/tmp/renovate/cache\":\"/tmp/renovate/cache\" -w \"/tmp/renovate/repos/github/PicnicSupermarket/picnic-scratch\" docker.io/renovate/pip bash -l -c \"python \\\"renovate-pip_setup-extract.py\\\" \\\"python-package-test/setup.py\\\"\"",
         "stdout": "",
         "stderr": "Traceback (most recent call last):\n  File \"renovate-pip_setup-extract.py\", line 46, in <module>\n    invoke()\n  File \"/usr/lib/python3.7/unittest/mock.py\", line 1255, in patched\n    return func(*args, **keywargs)\n  File \"renovate-pip_setup-extract.py\", line 39, in invoke\n    load_source('_target_setup_', sys.argv[-1])\n  File \"renovate-pip_setup-extract.py\", line 12, in load_source\n    return vars(SourceFileLoader('mod', path).load_module())\n  File \"<frozen importlib._bootstrap_external>\", line 407, in _check_name_wrapper\n  File \"<frozen importlib._bootstrap_external>\", line 907, in load_module\n  File \"<frozen importlib._bootstrap_external>\", line 732, in load_module\n  File \"<frozen importlib._bootstrap>\", line 265, in _load_module_shim\n  File \"<frozen importlib._bootstrap>\", line 696, in _load\n  File \"<frozen importlib._bootstrap>\", line 677, in _load_unlocked\n  File \"<frozen importlib._bootstrap_external>\", line 728, in exec_module\n  File \"<frozen importlib._bootstrap>\", line 219, in _call_with_frames_removed\n  File \"python-package-test/setup.py\", line 37, in <module>\n    with open(\"README.md\") as f:\nFileNotFoundError: [Errno 2] No such file or directory: 'README.md'\n",

[rarkins]

I don't have any objection to refactoring so that we set the cwd to be the package file's own directory, but we'll want to make sure we still map the repo's root location in the volume as is currently done, in case the file depends on any files higher up.

[hisener]

Created #8319 and #8320.