UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0

Steps to reproduce the problem:
1. Extract example.tgz
2. Open dev tools - network tab
3. Disable cache
4. Open simple.html from extracted folder

or 

1. Open dev tools - network tab
2. Disable cache
3. Open https://jsfiddle.net/ggb8otLd/
4. Run example

Problem does not occure every time, esspecially in jsfiddler.

What is the expected behavior?
xxx.js file is loaded once.

What went wrong?
xxx.js file is loaded twice.

Did this work before? No 

Chrome version: 57.0.2987.133 (64-bit)  Channel: stable
OS Version: 
Flash Version: Shockwave Flash 25.0 r0

Simple case, when second javascript file is loaded from disk cache is not big problem. But if second file has no-cache headers, it will be loaded from server twice.
 

Deleted: s13.png 27.6 KB

	s13.png 27.6 KB View Download

Deleted: example.tgz 344 bytes

example.tgz 344 bytes Download