Add a test for read-tree -u --reset with a D/F conflict

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1005-read-tree-reset.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+test_description='read-tree -u --reset'
+
+. ./test-lib.sh
+
+# two-tree test
+
+test_expect_success 'setup' '
+  git init &&
+  mkdir df &&
+  echo content >df/file &&
+  git add df/file &&
+  git commit -m one &&
+  git ls-files >expect &&
+  rm -rf df &&
+  echo content >df &&
+  git add df &&
+  echo content >new &&
+  git add new &&
+  git commit -m two
+'
+
+test_expect_failure 'reset should work' '
+  git read-tree -u --reset HEAD^ &&
+  git ls-files >actual &&
+  diff -u expect actual
+'
+
+test_done