lib: remove broken NODE_MODULE_CONTEXTS feature

[bnoordhuis]

This feature has no tests and has been broken for ages, see for example
#1160. Don't bother fixing it, it's
pretty much broken by design and there can't be too many users because
it's almost undocumented. A quick Google search suggests that it causes
more grief than joy to the few that do use it. Remove it.

R=@iojs/tc

https://jenkins-iojs.nodesource.com/view/iojs/job/iojs+any-pr+multi/306/

[cjihrig]

LGTM. CI looks good.

[vkurchatkin]

why is this semver minor?

[bnoordhuis]

@vkurchatkin As opposed to? Major or patch?

[vkurchatkin]

@bnoordhuis looks like major to me

[bnoordhuis]

@vkurchatkin I'd agree if it weren't broken, but it is and has been since at least 2013. I think that makes it eligible for quick removal, particularly when you consider that no one bothered to report it here or at joyent/node until now.

(Also, google for it - all the links are about people having issues with it.)

[chrisdickinson]

@bnoordhuis If it was broken and no one uses it, I'd be okay with knocking this down to semver-patch.

[vkurchatkin]

this is still a breaking change, isn't it? I have no idea why this feature exists but just removing it seems not right. Why not just deprecate it as usual?

[bnoordhuis]

Because it's broken and evidently no one uses it. I'm all for keeping working code working but I don't think that's a factor here.

[cjihrig]

+1 for patch. Can't be a breaking change if it's already broken.

[bnoordhuis]

Thanks everyone. I've landed it in f58e596. If it turns out someone does have a non-broken use case for it (unlikely but hey), we'll just revert it.