/usr/share/common-lisp/source/ is in cl-closer-mop 2:0.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/common-lisp/source/closer-mop/
/usr/share/common-lisp/source/closer-mop/closer-allegro.lisp
/usr/share/common-lisp/source/closer-mop/closer-clisp.lisp
/usr/share/common-lisp/source/closer-mop/closer-clozure.lisp
/usr/share/common-lisp/source/closer-mop/closer-cmu.lisp
/usr/share/common-lisp/source/closer-mop/closer-ecl.lisp
/usr/share/common-lisp/source/closer-mop/closer-lispworks.lisp
/usr/share/common-lisp/source/closer-mop/closer-mcl.lisp
/usr/share/common-lisp/source/closer-mop/closer-mop-packages.lisp
/usr/share/common-lisp/source/closer-mop/closer-mop-shared.lisp
/usr/share/common-lisp/source/closer-mop/closer-mop-system.cl
/usr/share/common-lisp/source/closer-mop/closer-mop.asd
/usr/share/common-lisp/source/closer-mop/closer-sbcl.lisp
/usr/share/common-lisp/source/closer-mop/closer-scl.lisp
/usr/share/common-lisp/source/closer-mop/features.lisp