[PATCH 0/6] fix repack.packKeptObjects regression in v2.0

Here's a cleaned up version of the fix I posted earlier, with related fixes on top.

  [1/6]: repack: do not accidentally pack kept objects by default

    This is the most critical one for 'maint', as it fixes the
    regression for people who are not using bitmaps at all.

  [2/6]: repack: respect pack.writebitmaps

    We probably want to apply this one to maint, too, as the first one
    breaks people depending on repack.packKeptObjects being impacted by
    pack.writebitmaps (it never worked properly, but the breakage fixed
    by the first patch covered it up).

  [3/6]: repack: s/write_bitmap/&s/ in code
  [4/6]: pack-objects: stop respecting pack.writebitmaps
  [5/6]: repack: simplify handling of --write-bitmap-index
  [6/6]: repack: introduce repack.writeBitmaps config option

    These ones can go the normal route, but see the regression comments in
    4/6.

-Peff