rebase 的实现:原 commit 去哪了

  $ git log --format='%s  author=%an  committer=%cn' main..feature
  F3  author=Alice  committer=Alice
  F2  author=Alice  committer=Alice
  F1  author=Alice  committer=Alice
  $ git log --graph --format='%s  author=%an  committer=%cn' main..feature; git log --oneline -1 main | sed -E 's/^[0-9a-f]+ /main 的末端: /'
  * F3  author=Alice  committer=Bob
  * F2  author=Alice  committer=Bob
  * F1  author=Alice  committer=Bob
  main 的末端: M3
  旧提交与新提交对应(同样的改动,不同的 parent,所以 hash 不同):
    旧F1 → 新F1   tree 相同? False  parent: M1 → M3
    旧F2 → 新F2   tree 相同? False  parent: 旧F1 → 新F1
    旧F3 → 新F3   tree 相同? False  parent: 旧F2 → 新F2
  新提交的 tree 都和旧的不同,因为每个新提交都建立在 M3 之上,tree 里多了 m2、m3(以第 1 个为例):
   旧F1 的文件: a f1 | 新F1 的文件: a f1 m2 m3

  ORIG_HEAD 指向旧F3: True;有多少个分支包含旧F3: 0
  $ git reflog -8 --format='%gd: %gs'
  HEAD@{0}: rebase (finish): returning to refs/heads/feature
  HEAD@{1}: rebase (pick): F3
  HEAD@{2}: rebase (pick): F2
  HEAD@{3}: rebase (pick): F1
  HEAD@{4}: rebase (start): checkout main
  HEAD@{5}: checkout: moving from main to feature
  HEAD@{6}: commit: M3
  HEAD@{7}: commit: M2
  $ git range-diff main ORIG_HEAD feature
  1:  c58861a = 1:  15e5082 F1
  2:  e30e803 = 2:  19aa103 F2
  3:  7f32687 = 3:  04039c8 F3

  $ git rebase main 2>&1 | head -3; ls .git/rebase-merge | tr "\n" " "; echo
  Rebasing (1/3)
  Rebasing (2/3)
  Auto-merging f2
  CONFLICT (add/add): Merge conflict in f2
  error: could not apply e30e803... F2
  author-script done drop_redundant_commits end git-rebase-todo git-rebase-todo.backup head-name interactive message msgnum no-reschedule-failed-exec onto orig-head patch r
  $ cd .git/rebase-merge; for f in head-name onto orig-head msgnum end; do printf "%-10s" $f; cat $f | sed -E "s/[0-9a-f]{40}/<sha40>/"; done; echo "--- git-rebase-todo:"; cat git-rebase-todo | sed -E "s/^(pick|p) [0-9a-f]+/\1 <sha>/"; echo "--- done:"; cat done | sed -E "s/^(pick|p) [0-9a-f]+/\1 <sha>/"
  head-name refs/heads/feature
  onto      <sha40>
  orig-head <sha40>
  msgnum    2
  end       3
  --- git-rebase-todo:
  pick <sha> # F3
  --- done:
  pick <sha> # F1
  pick <sha> # F2
  $ git status | sed -n 1,4p
  interactive rebase in progress; onto a0f5b01
  Last commands done (2 commands done):
     pick c58861a # F1
     pick e30e803 # F2
  $ GIT_EDITOR=true git rebase --continue 2>&1 | tail -1
  Rebasing (3/3)
  Successfully rebased and updated refs/heads/feature.
  完成后 .git/rebase-merge 还存在吗: False

  $ git rebase main 2>&1 | sed -E "s/[0-9a-f]{7,}/<sha>/g"; git log --format=%s main..feature
  warning: skipped previously applied commit <sha>
  hint: use --reapply-cherry-picks to include skipped commits
  hint: Disable this message with "git config set advice.skippedCherryPicks false"
  Rebasing (1/1)
  Successfully rebased and updated refs/heads/feature.
  F1
  $ git cherry -v main feature | sed -E "s/[0-9a-f]{40}/<sha40>/"
  + <sha40> F1

  $ git rebase main 2>&1 | head -2
  Current branch feature is up to date.