revision traversal: --remove-empty fix (take #2).

Marco Costalba reports that --remove-empty omits the commit that
created paths we are interested in.  try_to_simplify_commit()
logic was dropping a parent we introduced those paths against,
which I think is not what we meant.  Instead, this makes such
parent parentless.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/revision.c b/revision.c
index 03085ff..73fba5d 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -317,12 +317,16 @@ static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
                case TREE_NEW:
                        if (revs->remove_empty_trees &&
                            same_tree_as_empty(p->tree)) {
-                               /* We are adding all the specified paths from
-                                * this parent, so the parents of it is
-                                * not interesting, but the difference between
-                                * this parent and us still is interesting.
+                               /* We are adding all the specified
+                                * paths from this parent, so the
+                                * history beyond this parent is not
+                                * interesting.  Remove its parents
+                                * (they are grandparents for us).
+                                * IOW, we pretend this parent is a
+                                * "root" commit.
                                 */
-                               p->object.flags |= UNINTERESTING;
+                               parse_commit(p);
+                               p->parents = NULL;
                        }
                /* fallthrough */
                case TREE_DIFFERENT: