/usr/share/lintian/overrides/libnspr4-dbg is in libnspr4-dbg 2:4.13.1-0ubuntu0.14.04.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | # License says GPL 2 or subsequent, so pointing to the latest version is fine
libnspr4-dbg: copyright-refers-to-versionless-license-file usr/share/common-licenses/GPL
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