Merge branch 'jk/config-warn-on-inaccessible-paths'

The attribute system may be asked for a path that itself or its leading directories no longer exists in the working tree. Failure to open per-directory .gitattributes with error status other than ENOENT and ENOTDIR are diagnosed. * jk/config-warn-on-inaccessible-paths: attr: failure to open a .gitattributes file is OK with ENOTDIR