CSS Validator and SVG

If I use the direct input tab, I can can validate CSS extracted from an SVG
style element..

I can also paste an entire SVG file, and the validator extracts the the CSS
from the style element and validates it.

I can switch to the validator's file tab and upload the same SVG file. The
validator extracts the CSS from the style element and validates it.

However, I cannot do the validation from the validator's URI tab.for the
same file content. I paste the URI in the box, but I get the error message:

Target:
https://upload.wikimedia.org/wikipedia/commons/1/18/Eukaryotic_DNA_replication.svg
I/O Error: Unknown mime type : image/svg+xml

I went to the FAQ page, and there is a note about about requiring a
text/css mimetype, but I can feed an HTML URI to the validator, and it
works fine.

The tool can validate CSS in SVG files already. If the URI fetch returns
the image/svg+xml mimetype, then it should do the same processing that it
does when an SVG file is pasted into direct input or upoaded as a file.

Thanks,
Jerry