Merge branch 'tb/pseudo-merge-bugfixes'

Fixes many bugs in pseudo-merge code.

* tb/pseudo-merge-bugfixes:
  pack-bitmap: prevent pattern leak on pseudo-merge re-assignment
  Documentation: fix broken `sampleRate` in gitpacking(7)
  pack-bitmap: reject pseudo-merge "sampleRate" of 0
  pack-bitmap: parse commits in `find_pseudo_merge_group_for_ref()`
  pack-bitmap: fix pseudo-merge lookup for shared commits
  pack-bitmap: fix inverted binary search in `pseudo_merge_at()`
  pack-bitmap-write: sort pseudo-merge commit lookup table in pack order
  t5333: demonstrate various pseudo-merge bugs
  t/helper: add 'test-tool bitmap write' subcommand