/usr/lib/ghc-doc/hoogle/deepseq.txt is in ghc-doc 7.6.3-21.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/ghc-doc/html/libraries/deepseq-1.3.0.1/deepseq.txt
/usr/lib/ghc-doc/hoogle/../../../share/doc/ghc-doc/html/libraries/deepseq-1.3.0.1/deepseq.txt