diff --git a/Documentation/RelNotes-1.6.3.1.txt b/Documentation/RelNotes-1.6.3.1.txt
index 98c02250bb69f70b4c08d4f7e535909ed4a5d6f5..2400b72ef7bcb53dadced93634a7df2ea96cc34f 100644
--- a/Documentation/RelNotes-1.6.3.1.txt
+++ b/Documentation/RelNotes-1.6.3.1.txt
@@ -4,9 +4,7 @@ GIT v1.6.3.1 Release Notes
 Fixes since v1.6.3
 ------------------
 
---
-exec >/var/tmp/1
-O=v1.6.3
-echo O=$(git describe maint)
-git shortlog $O..maint
-
+* "git checkout -b new-branch" with a staged change in the index
+  incorrectly primed the in-index cache-tree, resulting a wrong tree
+  object to be written out of the index.  This is a grave regression
+  since the last 1.6.2.X maintenance release.
diff --git a/builtin-checkout.c b/builtin-checkout.c
index 15f0c32c7a7ed62afe31e3bafb2d7306ba4a3402..dc4bfb5fc08d51644435f158e3b07ffe518ac419 100644
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -365,17 +365,14 @@ static int merge_working_tree(struct checkout_opts *opts,
 	int ret;
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 	int newfd = hold_locked_index(lock_file, 1);
-	int reprime_cache_tree = 0;
 
 	if (read_cache() < 0)
 		return error("corrupt index file");
 
-	cache_tree_free(&active_cache_tree);
 	if (opts->force) {
 		ret = reset_tree(new->commit->tree, opts, 1);
 		if (ret)
 			return ret;
-		reprime_cache_tree = 1;
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -411,9 +408,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 		init_tree_desc(&trees[1], tree->buffer, tree->size);
 
 		ret = unpack_trees(2, trees, &topts);
-		if (ret != -1) {
-			reprime_cache_tree = 1;
-		} else {
+		if (ret == -1) {
 			/*
 			 * Unpack couldn't do a trivial merge; either
 			 * give up or do a real merge, depending on
@@ -457,8 +452,6 @@ static int merge_working_tree(struct checkout_opts *opts,
 		}
 	}
 
-	if (reprime_cache_tree)
-		prime_cache_tree(&active_cache_tree, new->commit->tree);
 	if (write_cache(newfd, active_cache, active_nr) ||
 	    commit_locked_index(lock_file))
 		die("unable to write new index file");
diff --git a/t/t2014-switch.sh b/t/t2014-switch.sh
new file mode 100755
index 0000000000000000000000000000000000000000..ccfb1471135396cfc2a2dfca10697b2778c79445
--- /dev/null
+++ b/t/t2014-switch.sh
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+test_description='Peter MacMillan'
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo Hello >file &&
+	git add file &&
+	test_tick &&
+	git commit -m V1 &&
+	echo Hello world >file &&
+	git add file &&
+	git checkout -b other
+'
+
+test_expect_success 'check all changes are staged' '
+	git diff --exit-code
+'
+
+test_expect_success 'second commit' '
+	git commit -m V2
+'
+
+test_expect_success 'check' '
+	git diff --cached --exit-code
+'
+
+test_done