For me, linking to (external) links works using the protocol (https:// in this case):

L<https://rt.cpan.org/Public/Dist/Display.html?Name=WWW-Mechanize-Chro
+me>
[download]

Linking to (external) images still works, as exhibited by Spreadsheet::WriteExcel:

=begin html

<center>
<img src="http://homepage.eircom.net/~jmcnamara/perl/data_validation.j
+pg" alt="The output from the above example"/>
</center>

=end html
[download]

So, it seems that Emacs::PDE fell prey to the changes in the POD renderer, but things should be fixable. If you want to use dist-relative https:// links, I think you can use the following as the target:

L<https://metacpan.org/pod/distribution/Emacs-PDE/lisp/doc/pde/index.h
+tml>  - PDE User Guide
[download]

... but MetaCPAN doesn't seem to render the HTML files as HTML, which I suppose is an anti-spam measure.