Case-insensitivity issue running yarn in docker on a volume bind-mounted from a Mac "EEXIST: file already exists"

[twitchard]

What is the current behavior?

I was running yarn in a bind-mounted directory from Mac OS X, and getting an error message (see this repo for the package.json, etc)

EEXIST: file already exists, mkdir '/test/node_modules/typescript/lib/zh-TW

I looked inside the filesystem and the directory was indeed there, but lower-cased.

If I bind-mount the yarn cache as well, however, the issue stops. (That's a good enough solution to my problem, and probably what I should be doing anyway.)
I think the cause of this relates somehow to a problem with yarn handling the situation where the yarn cache is located on a case-sensitive filesystem, but the destination node_modules is on a case-insensitive filesystem. But I can't believe nobody's ever hit this before -- there must also be something unique about this particular set of dependencies and the cases of the filenames.

If the current behavior is a bug, please provide the steps to reproduce.

Here they are:
https://github.com/twitchard/case-insensitive-yarn-failure

What is the expected behavior?

• Ideally Yarn would find some way to succeed.
• Failing that, Yarn could detect this situation and emit a useful warning with a suggested course of action?
• Failing that, this issue report is here, and hopefully the SEO is good enough for the next person who hits this to understand this problem faster than I did.

Please mention your node.js, yarn and operating system version.

node: v8.14.0

Host OS: macOS High Sierra 10.13.6

Container OS: Alpine latest

Yarn: Tested on both v1.6.0 and v1.13.0