Bug#558404: Spaces in sources.list.d filenames also don't work

[Andrew Bobulsky <rulerof@gmail.com>]

Hi,

I got bit by this same issue 10 years later.

The files in sources.list.d cannot have spaces in their names for this
same underlying reason.

This took a lot of time to figure out because this restriction doesn't
appear to be mentioned in the doc.

Regards,
Andrew