Merge branch 'jc/pathspec-match-with-common-prefix'

"git ls-files '(attr:X)D/'" that triggers the common prefix
optimization codepath failed to read from "D/.gitattributes",
which has been corrected.

* jc/pathspec-match-with-common-prefix:
  dir: match "attr" pathspec magic with correct paths
  t6135: attr magic with path pattern

diff --cc dir.c
Simple merge