Merge branch 'jc/diff-no-index-d-f'

The usual "git diff" when seeing a file turning into a directory
showed a patchset to remove the file and create all files in the
directory, but "git diff --no-index" simply refused to work.  Also,
when asked to compare a file and a directory, imitate POSIX "diff"
and compare the file with the file with the same name in the
directory, instead of refusing to run.

* jc/diff-no-index-d-f:
diff-no-index: align D/F handling with that of normal Git
diff-no-index: DWIM "diff D F" into "diff D/F F"

diff --combined t/t4053-diff-no-index.sh
index 075ece6db16f9c313504559d95c5b1dc6b4c2e07,596dfe712d5e870cbc1a5b88358127d80d0f570c..6eb83211b593ecea798eba3790b9c76fc7d3aa60
--- 1/t/t4053-diff-no-index.sh
--- 2/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@@ -17,8 -17,8 +17,8 @@@ test_expect_success 'setup' 
  '
  
  test_expect_success 'git diff --no-index directories' '
 -      git diff --no-index a b >cnt
 -      test $? = 1 && test_line_count = 14 cnt
 +      test_expect_code 1 git diff --no-index a b >cnt &&
 +      test_line_count = 14 cnt
  '
  
  test_expect_success 'git diff --no-index relative path outside repo' '
@@@ -55,4 -55,38 +55,38 @@@ test_expect_success 'git diff --no-inde
        )
  '
  
+ test_expect_success 'diff D F and diff F D' '
+       (
+               cd repo &&
+               echo in-repo >a &&
+               echo non-repo >../non/git/a &&
+               mkdir sub &&
+               echo sub-repo >sub/a &&
+ 
+               test_must_fail git diff --no-index sub/a ../non/git/a >expect &&
+               test_must_fail git diff --no-index sub/a ../non/git/ >actual &&
+               test_cmp expect actual &&
+ 
+               test_must_fail git diff --no-index a ../non/git/a >expect &&
+               test_must_fail git diff --no-index a ../non/git/ >actual &&
+               test_cmp expect actual &&
+ 
+               test_must_fail git diff --no-index ../non/git/a a >expect &&
+               test_must_fail git diff --no-index ../non/git a >actual &&
+               test_cmp expect actual
+       )
+ '
+ 
+ test_expect_success 'turning a file into a directory' '
+       (
+               cd non/git &&
+               mkdir d e e/sub &&
+               echo 1 >d/sub &&
+               echo 2 >e/sub/file &&
+               printf "D\td/sub\nA\te/sub/file\n" >expect &&
+               test_must_fail git diff --no-index --name-status d e >actual &&
+               test_cmp expect actual
+       )
+ '
+ 
  test_done