The image referenced from html file in the sub directory won't be displayed

Problem/Motivation

There is a zip file which contains a HTML file "doc1.html" in the subdirectory "subdir1".
The "doc1.html" refers image file with relative path such like "images/pict.png", but the image file won't be displayed.

[zip file]
my_zip/index.html # contains <a href="subdir1/doc1.html">
my_zip/subdir1/doc1.html # contains <link rel="stylesheet" href="style/style.css">, <img src="images/pict.png">
my_zip/subdir1/style/style.css
my_zip/subdir1/images/pict.png

https://www.drupal.org/node/add/project-issue/minisite# →

Steps to reproduce

create zip which contains html file in the subdirectory
upload zip

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes