Fix gitmkdtemp: correct test for mktemp() return value

diff --git a/builtin-checkout.c b/builtin-checkout.c
index 05eee4ecc71d7a20d9faf59c849d3c693ae4cc8d..b76cd22776299955d1ff876b5668f2336b4321a2 100644 (file)
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -269,11 +269,10 @@ static int merge_working_tree(struct checkout_opts *opts,
                }
 
                /* 2-way merge to the new branch */
-               topts.initial_checkout = (!active_nr &&
-                                         (old->commit == new->commit));
+               topts.initial_checkout = is_cache_unborn();
                topts.update = 1;
                topts.merge = 1;
-               topts.gently = opts->merge;
+               topts.gently = opts->merge && old->commit;
                topts.verbose_update = !opts->quiet;
                topts.fn = twoway_merge;
                topts.dir = xcalloc(1, sizeof(*topts.dir));
@@ -295,7 +294,13 @@ static int merge_working_tree(struct checkout_opts *opts,
                        struct tree *work;
                        if (!opts->merge)
                                return 1;
-                       parse_commit(old->commit);
+
+                       /*
+                        * Without old->commit, the below is the same as
+                        * the two-tree unpack we already tried and failed.
+                        */
+                       if (!old->commit)
+                               return 1;
 
                        /* Do more real merge */
 
@@ -422,7 +427,7 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
        if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
                describe_detached_head("Previous HEAD position was", old.commit);
 
-       if (!old.commit) {
+       if (!old.commit && !opts->force) {
                if (!opts->quiet) {
                        fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
                        fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);