Yarn 1.9.x ignoring proxy env variables

[MattDiMu]

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

What is the current behavior?
After the version upgrade from yarn 1.7.x to 1.9.4 yarn no longer respects the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY.

If the current behavior is a bug, please provide the steps to reproduce.
Define the mentioned env variables (HTTP_PROXY, HTTPS_PROXY and NO_PROXY) on a system behind a corporate proxy and use it with yarn 1.7 and yarn 1.9.4 Only the former version will be able to connect to https://registry.yarnpkg.com.

What is the expected behavior?
yarn should respect these env variables like it used to do.

Please mention your node.js, yarn and operating system version.
win10 x64
node 8.11.3 (=latest LTS version)
yarn 1.9.4

@everyone having the same issues - as a workaround you may redefine the proxy settings using the global .yarnrc config:

yarn config set proxy <path>
yarn config set https-proxy <path>

[P0oOOOo0YA]

OK suppose i have proxy env variables that yarn uses but for some reason proxies are down. what is yarn behavior in this case? right now it keeps trying to connect shouldn't it at least prompt the use whether she want to connect directly? or a flog like yarn --direct install?