bug#26490: 25.1; package-buffer-info is incorrectly case-insensitive

[Steve Purcell]

> Why does it care at all?
> I thought the "filename ends here" was an ancient way of identifying
> files that might have been truncated in transit. It doesn't seem
> relevant in this day and age.
> And if that is what it's for, why should the case of the filename matter?
> So long as some "ends here" line is there, the file is ok.


Nonetheless, it has been part of the format expected by package.el for years.

Making package.el more permissive over time can lead to problems with packages 
in older Emacsen, a prime example being the recently-added 
backwards-incompatible support for version-less dependencies in the 
`Package-Requires` header: authors check their packages in a recent Emacs and 
then find that an older otherwise-compatible Emacs can’t even parse their 
package metadata.