1.9.2 - unable to get local issuer certificate with cafile

[dancoto]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
Running yarn add light-server returns

error An unexpected error occurred: "https://registry.yarnpkg.com/light-server: unable to get local issuer certificate"

This happens as of 1.9.2
It works on 1.7.0 with no configuration changes.

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

This is happening behind corporate proxy. I have custom .pem and internal registry.
I have an existing .pem file specified in my cafile property. I have also tried setting strict-ssl false as suggested by another issue that was resolved and I see no difference.
Run yarn add on any package returns this issue.
Running yarn add light-server returns

error An unexpected error occurred: "https://registry.yarnpkg.com/light-server: unable to get local issuer certificate"

See my masked .yarnrc below

{
    'version-tag-prefix': 'v',
    'version-git-tag': true,
    'version-commit-hooks': true,
    'version-git-sign': false,
    'version-git-message': 'v%s',
    'init-version': '1.0.0',
    'init-license': 'MIT',
    'save-prefix': '^',
    'bin-links': true,
    'ignore-scripts': false,
    'ignore-optional': false,
    registry: 'https://my-internal-repo',
    'strict-ssl': false,
    'user-agent': 'yarn/1.9.2 npm/? node/v10.7.0 darwin x64',
    cafile: '/location/to/cafile.pem',
    'ignore-engines': true,
    lastUpdateCheck: 1533139320603
}

What is the expected behavior?
It should add the package.

Please mention your node.js, yarn and operating system version.
Using Yarn 1.9.2 from Homebrew
Node => v10.7.0
Npm => 6.2.0

[AndreasSchouten]

Get a similar error with yarn 1.9.4.
Have set strict-ssl to false but get still an

Error: unable to get local issuer certificate

Seems yarn 1.9 ignores this flag?