gc: do not explode objects which will be immediately pruned

diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 93c92814cf28855aee87cabf4a3b906e11a36125..df6c4c8819e7903f34cd6dc6bb0078a6cddac310 100644 (file)
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -130,6 +130,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
                  PARSE_OPT_NONEG, exclude_per_directory_cb },
                OPT_SET_INT('i', NULL, &opts.index_only,
                            "don't check the working tree after merging", 1),
+               OPT__DRY_RUN(&opts.dry_run, "don't update the index or the work tree"),
                OPT_SET_INT(0, "no-sparse-checkout", &opts.skip_sparse_checkout,
                            "skip applying sparse checkout filter", 1),
                OPT_SET_INT(0, "debug-unpack", &opts.debug_unpack,
@@ -219,7 +220,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
        if (unpack_trees(nr_trees, t, &opts))
                return 128;
 
-       if (opts.debug_unpack)
+       if (opts.debug_unpack || opts.dry_run)
                return 0; /* do not write the index out */
 
        /*