Please clarify the license for the project
What is the intended actual license for the project?
debian/copyright claims it's 'GPL-2 or later'. However, I can't find any real grounds for the 'or later' there.
All C sources reference
COPYING which in turn is verbatim copy of GPL-2. It contains the 'or later' clause only as an example of copyright notice, so that can't really be taken as clear allowance to use later version.
GExiv2.py indicates 'LGPL-2.1 or later'. I'm not convinced it's allowed to combine it (even indirectly via introspection) to a library that's using more restrictive GPL license. However, IANAL, so I'm not going to argue about that.
test_metadata.py indicates 'GPL-3 or later'. Again, it is unclear whether it is valid to combine it with 'GPL-2' sources.