[PATCH 3/4] read-tree -m A B: prime cache-tree from the switched-to tree

[Junio C Hamano <gitster@pobox.com>]

When switching to a new branch with "read-tree -m A B", the resulting
index must match tree B and we can prime the cache tree with it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin-read-tree.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 9cd7d07..391d709 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -199,9 +199,14 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	 * "-m ent" or "--reset ent" form), we can obtain a fully
 	 * valid cache-tree because the index must match exactly
 	 * what came from the tree.
+	 *
+	 * The same holds true if we are switching between two trees
+	 * using read-tree -m A B.  The index must match B after that.
 	 */
 	if (nr_trees == 1 && !opts.prefix)
 		prime_cache_tree(&active_cache_tree, trees[0]);
+	else if (nr_trees == 2 && opts.merge)
+		prime_cache_tree(&active_cache_tree, trees[1]);
 
 	if (write_cache(newfd, active_cache, active_nr) ||
 	    commit_locked_index(&lock_file))
-- 
1.6.3.rc1.18.g66996