/usr/share/doc/ruby-rspec-mocks/changelog.Debian.gz is in ruby-rspec-mocks 3.4.0c3e0m1s1-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/ruby-rspec-mocks/../ruby-rspec-support/changelog.Debian.gz