How to avoid Hugo stripping unicode characters from page's slug?

I am working with Chinese content (using UTF-8), while most of the time it generates the right url, sometimes it strips certain Chinese characters from URL.

Some examples of these characters are:

When generating a page for each character, i.e.: example.com/post/〇 it generates empty paths example.com/post// .

Steps

To reproduce the bug, add

slug: "foo〇○〡〤〢⺮〣21三bar"

in the front matter of any page Hugo will generate the following stripped path:

http://localhost:1313/post/foo21三bar/` 

removing 〇○〡〤〢⺮〣.

Tested with latest Hugo release: Hugo Static Site Generator v0.30.2 linux/amd64 BuildDate: 2017-10-19T08:34:27-03:00

(x-post: stackoverflow.com)

Hugo sanitizes the path, “allowing only a predefined set of special Unicode characters.” Your examples are not in that predefined set.