Bug overview description.
I'm not sure if this is the real cause of the bug, but it is the only thing I noticed is different from the normal.

When uploading an image that contains japanese characters, an error is given and the upload does not happen.

What part(s) of the site page(s) are affected?
Both upload pages: https://e621.net/post/upload and https://e621.net/post/upload?use_new=true

What is the expected behavior?
To upload correctly.

What actual behavior is given instead?
An HTTP error.

Time of incident (if applicable).

Can you reproduce the bug every time?
Yes, every time.

What steps did you take to replicate this bug?
Go to the upload form, choose the upload from URL field, and put this image: http://d.facdn.net/art/uleez/1561742614/1561742592.uleez_%E7%8F%8D%E7%8F%A0%E5%A5%B6%E8%8C%B6.jpg

Errors or other messages returned (if any).
When upload the following message is given:

Error: Source couldn't be opened: HTTP error code: 404 Not Found