Merge branch 'jc/check-attr-honor-working-tree' into maint

"git check-attr" when working on a repository with a working tree did not work well when the working tree was specified via the --work-tree (and obviously with --git-dir) option. * jc/check-attr-honor-working-tree: check-attr: move to the top of working tree when in non-bare repository t0003: do not chdir the whole test process