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

diff --cc attr.c
Simple merge