/usr/share/doc/emacsen-common/debian-emacs-policy.gz section 8 asks lisp
add-ons to add load-path directories with `debian-pkg-add-load-path-item'
rather than directly modifying `load-path' the way 50mgp.el does.

I believe debian-pkg-add-load-path-item is available as of "sarge"
emacsen-common 1.4.14 of June 2002.  It aims to keep /usr/local ahead of
packaged lisp dirs so that anything the sysadmin puts in /usr/local has
precedence.