Bug#1002053: lintian: false positive inconsistent-appstream-metadata-license (gpl-2.0+ != gpl-2+)

[Nicholas D Steeves <sten@debian.org>]

Package: lintian
Version: 2.114.0
Severity: normal

Hi,

Gpl-2+ (used in d/copyright) is equivalent to gpl-2.0+ used in
appstream metadata, so this is a false positive.  Were GNU to
hypothetically release a GPL 2.1, and were upstream to switch to it,
the onus would be on the Debian maintainer to update d/copyright.  It
also seems wrong to emit this at the warning level for this specific
case.

If lintian is encouraging maintainers to use the "gpl-2.0+" notation
rather than gpl-2+ in d/copyright, then it should emit a different
(lower severity than warning) tag for that case.

It seems clear to me that (gpl-2.0+ = gpl-2+), so it looks like the
correct approach is to use a table of equivalent license notations to
prevent the false positive.  Apologies if bias has prevented me from
deeper analysis or seeing other solutions.

Thanks!
Nicholas