@imports using HTTPS don't work behind a proxy

[pitaj]

• Source:

@import url(https://fonts.googleapis.com/css?family=Roboto:300,400,500,700);

• Expected output:

/* contents of referenced file */

• Error:

Error: Broken @import declaration of "https://fonts.googleapis.com/css?family=Roboto:300,400,500,700" - timeout

• Options: No options object provided, defaults
• Version: clean-css@3.4.20 used via postcss@1.0.2
• OS: Ubuntu 16.04

Ref #612 and NodeBB/NodeBB#5368

[jakubpawlowicz]

This is actually a duplicate of #755. It's still scheduled for 4.1.