Lintian tag information: license-problem-undefined-license (type: error)

Description (from lintian-explain-tags)

Your copyright file references a license that is not defined. Due to
copyright law or treaties, files that are not available under a defined
license are non-free and non-re-distributable.

Referencing an undefined license could mean the file cannot be distributed
in Debian or it could simply mean that the existing license needs to be
documented. In both cases, the copyright file should be updated to reflect
reality.

Please re-package the package without the file (if possible) or ask the
FTP-masters to remove the package.

If the package has been uploaded to Debian before, and if affected files
cannot be distributed in Debian please remember to also notify
snapshot.debian.org about this package containing a non-distributable
file.

Please refer to https://ftp-master.debian.org/REJECT-FAQ.html for details.

Visibility: error
Show-Always: no
Check: debian/copyright/dep5

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