pack-bitmap.c: avoid exposing absolute paths
In "open_midx_bitmap_1()" and "open_pack_bitmap_1()", when we find that
there are multiple bitmaps, we will only open the first one and then
leave warnings about the remaining pack information, the information
will contain the absolute path of the repository, for example in a
alternates usage scenario. So let's hide this kind of potentially
sensitive information in this commit.
Found-by: XingXin <moweng.xx@antgroup.com>
Signed-off-by: Teng Long <dyroneteng@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>