[ Rush ] Yarn skipping optional dependencies on rush link.

[factoidforrest]

Some dependencies get skipped as optional, and then webpack throws on fsevents and a few other osx specific packages. Is there a way to force rush to install these? It seems weird that I get the warning on the link step and not the install step.

I set ignore-optional=false in /common/config/rush/.npmrc. Didn't fix it.

I'm seeing something like this on a few packages on rush link:

LINKING: api
Skipping optional dependency: dtrace-provider
Skipping optional dependency: mv
Skipping optional dependency: safe-json-stringify
Skipping optional dependency: dtrace-provider
Skipping optional dependency: fsevents
Skipping optional dependency: safe-json-stringify
Skipping optional dependency: bcrypt-pbkdf
Skipping optional dependency: ecc-jsbn
Skipping optional dependency: jsbn
Skipping optional dependency: tweetnacl

[factoidforrest]

discussed and assigned in #761