checkout: Don't crash when switching away from an invalid branch.

diff --git a/builtin-commit.c b/builtin-commit.c
index c870037b07ca00aeeeb369fdae98c9b828be0af2..b563a0d67cedc66825692863d9e57001fba35348 100644 (file)
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -320,7 +320,8 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
                die("unable to write new_index file");
 
        fd = hold_lock_file_for_update(&false_lock,
-                                      git_path("next-index-%d", getpid()), 1);
+                                      git_path("next-index-%d", getpid()),
+                                      LOCK_DIE_ON_ERROR);
 
        create_base_index();
        add_remove_files(&partial);
@@ -639,7 +640,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
                active_cache_tree = cache_tree();
        if (cache_tree_update(active_cache_tree,
                              active_cache, active_nr, 0, 0) < 0) {
-               error("Error building trees");
+               error("Error building trees; the index is unmerged?");
                return 0;
        }