Missing copyright clause of debian directory

Hi,

I start working on adopting web-mode whose previous maintainer Thomas
Koch[1] became MIA (see Bug#1019031).  When working on d/copyright, it
turns out that there was only one copyright section that covered "Files:
*" with upstream copyright owners but no separate section for "debian/*"
(see also the d/copyright of the snapshot of version 17.0.2-1[2]).
After checking the upstream copyright[3], I don't see the previous
maintainer in the list of copyright owners, therefore I believe the
current d/copyright is at mistake by covering the content in debian
directory under "Files: *".

I'd like to change this situation by adding a separate section covering
"File: debian/*" and attribute the copyright to the previous maintainer,
but currently there are some complications I am not sure how to handle.
Upstream changed their license from GPL-2 to GPL-3 in 2022, while the
previous maintainer last worked on this back in 2020, so I believe I am
obliged to update upstream license to GPL-3.  Following suggestions from
my reviewer Nicholas, I'm here to consult [email protected] for
suggestions.  So at high level I currently have 2 questions:

1. whether I can add the new copyright section to cover debian/*, and

2. whether I should use GPL-2 as when the previous maintainer last
worked on this or I can use GPL-3 to match upstream version as well?

Looking forward to any suggestions.  TIA!

-- 
Xiyue Deng

[1] https://qa.debian.org/developer.php?email=thomas%40koch.ro
[2] https://sources.debian.org/src/web-mode/17.0.2-1/debian/copyright/
[3] https://github.com/fxbois/web-mode/blob/master/web-mode.el

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