pack-bitmap: remove checks before bitmap_free

In pack-bitmap.c:find_boundary_objects(), the roots_bitmap is only freed if cascade_pseudo_merges_1() fails. However, cascade_pseudo_merges_1() uses roots_bitmap as a mutable reference without taking ownership of it. As a result, if cascade_pseudo_merges_1() succeeds, roots_bitmap is leaked. And this leak currently lacks a dedicated test to detect it. To fix this leak, remove if cascade_pseudo_merges_1() succeed check and always calling bitmap_free(roots_bitmap); To trigger this leak, we need roots_bitmap that contains at least one pseudo merge. So that we can use pseudo merge bitmap when we compute roots reachable bitmap. Here we create two commits: first A then B. Add A to the pseudo-merge and perform a traversal over the range A..B. In this scenario, the "haves" set will be {A}, and cascade_pseudo_merges_1 will succeed, thereby exposing the leak due to the missing roots_bitmap cleanup. Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn> Signed-off-by: Junio C Hamano <gitster@pobox.com>