add PIPENV_SKIP_LOCK envvar, and suitable doc

[devxpy]

Fixes #2200.

🐍🏕️

[techalchemy]

As I said in the issue, isn’t this covered already by our use of auto_envvar_prefix?

[devxpy]

@techalchemy. I am not sure, can you please tell me the env var to set, so that I can test it out myself?

[devxpy]

Weird, search results don't seem to show any mention of auto_envvar_prefix

https://github.com/pypa/pipenv/search?q=auto_envvar_prefix&unscoped_q=auto_envvar_prefix

What am I missing here?

[techalchemy]

The option I was looking for relates to this approved enhancement proposal which describes the implementation we plan to adopt which uses click's auto_envvar_prefix option which you can read about in click's documentation. I'd prefer to see a refactor in that direction than to keep adding environment variables that are manually defined and maintained.

[techalchemy]

Seems like that option includes the command name in between, i.e. PIPENV_LOCK_SKIP_LOCK in order to work, so I'll include this

[devxpy]

@techalchemy, Okay will merge master

[techalchemy]

I merged your branch into the one I have queued up to merge already