Merge branch 'jk/index-pack-maint'

"index-pack --strict" has been taught to make sure that it runs the final object integrity checks after making the freshly indexed packfile available to itself. * jk/index-pack-maint: index-pack: correct install_packed_git() args index-pack: handle --strict checks of non-repo packs prepare_commit_graft: treat non-repository as a noop