Lock Fails as Part of Install, Succeeds with Skipping Lock then Locking

[PatrickFeeney]

Issue description

pipenv install fails but pipenv install --skip-lock then pipenv lock succeeds. Attempts to reproduce this bug suggest that the issue might arise from installing categories that share dependencies.

Expected result

pipenv install succeeds and there is no difference in behavior for the two methods.

Actual result

pipenv install fails but pipenv install --skip-lock then pipenv lock succeeds.

Steps to replicate

Download the following files and remove the txt extension required to upload to GitHub:
fail_Pipfile.lock.txt
pass_Pipfile.lock.txt
Pipfile.txt

In the directory with the Pipfile run pipenv install --categories "packages,torch_cpu". This should fail and produce a Pipfile.lock similar to the provided fail_Pipfile.lock. Run pipenv --rm to remove the failed environment and delete or rename the produced Pipfile.lock.

Again in the directory with the Pipfile, run pipenv install --categories "packages,torch_cpu" --skip-lock. This should succeed. Then run pipenv lock which should succeed and produce a Pipfile.lock similar to pass_Pipfile.lock.

---

$ pipenv --support

support.txt