Merge branch 'jc/maint-1.6.0-read-tree-overlay' into maint

* jc/maint-1.6.0-read-tree-overlay:
  read-tree A B C: do not create a bogus index and do not segfault

t/t1008-read-tree-overlay.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+
+test_description='test multi-tree read-tree without merging'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo one >a &&
+	git add a &&
+	git commit -m initial &&
+	git tag initial &&
+	echo two >b &&
+	git add b &&
+	git commit -m second &&
+	git checkout -b side initial &&
+	echo three >a &&
+	mkdir b &&
+	echo four >b/c &&
+	git add b/c &&
+	git commit -m third
+'
+
+test_expect_success 'multi-read' '
+	git read-tree initial master side &&
+	(echo a; echo b/c) >expect &&
+	git ls-files >actual &&
+	test_cmp expect actual
+'
+
+test_done
+

unpack-trees.c

@@ -49,7 +49,7 @@ static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 	memcpy(new, ce, size);
 	new->next = NULL;
 	new->ce_flags = (new->ce_flags & ~clear) | set;
-	add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
+	add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 }
 
 /* Unlink the last component and attempt to remove leading
@@ -286,9 +286,9 @@ static int unpack_nondirectories(int n, unsigned long mask,
 	if (o->merge)
 		return call_unpack_fn(src, o);
 
-	n += o->merge;
 	for (i = 0; i < n; i++)
-		add_entry(o, src[i], 0, 0);
+		if (src[i] && src[i] != o->df_conflict_entry)
+			add_entry(o, src[i], 0, 0);
 	return 0;
 }