git 在使用 --fixup 和 --autosquash 时让我非常头疼。我想举两个例子，一个工作得很好，另一个是一团糟。（git 版本 2.6.2）
工作示例：
第一次提交：
$ git init
$ printf '1\n' > test.file
$ git add test.file
$ git commit -m 'Insert 1 --> first line'
$ cat test.file
1
第二次提交（BUG）：
$ printf 'This is\na BUG\n' >> test.file
$ git commit -am 'Added line 2 and 3 with BUG'
$ cat test.file
1
This is
a BUG
第三次提交：
$ sed -i '2i 2' test.file
$ git commit -am 'Insert 2 --> second line'
$ cat test.file
1
2
This is
a BUG
第四次提交（修复）：
$ sed -i 's/a BUG/NOT a BUG/' test.file
$ git add test.file
$ git log --oneline
b021696 Insert 2 --> second line
2e18b8d Added line 2 and 3 with BUG
d7b60a1 Insert 1 --> first line
$ git commit --fixup HEAD~
$ cat test.file
1
2
This is
NOT a BUG
变基：
$ git log --oneline
fe99989 fixup! Added line 2 and 3 with BUG
b021696 Insert 2 --> second line
2e18b8d Added line 2 and 3 with BUG
d7b60a1 Insert 1 --> first line
$ git rebase -i --autosquash HEAD~3
[detached HEAD 6660b0e] Added line 2 and 3 with BUG
Date: Tue Nov 3 13:28:07 2015 +0100
1 file changed, 2 insertions(+)
Successfully rebased and updated refs/heads/master.
头痛示例：（唯一的区别是 BUGGY 提交是单行）
第一次提交：
$ git init
$ printf '1\n' > test.file
$ git add test.file
$ git commit -m 'Insert 1 --> first line'
$ cat test.file
1
第二次提交（BUG）：
$ printf 'This is a BUG\n' >> test.file
$ git commit -am 'Added line 2 with BUG'
$ cat test.file
1
This is a BUG
第三次提交：
$ sed -i '2i 2' test.file
$ git commit -am 'Insert 2 --> second line'
$ cat test.file
1
2
This is a BUG
第四次提交（修复）：
$ sed -i 's/a BUG/NOT a BUG/' test.file
$ git add test.file
$ git log --oneline
2b83fe7 Insert 2 --> second line
62cdd05 Added line 2 with BUG
0ee3343 Insert 1 --> first line
$ git commit --fixup HEAD~
$ cat test.file
1
2
This is NOT a BUG
变基：
$ git log --oneline
c3d3db7 fixup! Added line 2 with BUG
2b83fe7 Insert 2 --> second line
62cdd05 Added line 2 with BUG
0ee3343 Insert 1 --> first line
$ git rebase -i --autosquash HEAD~3
error: could not apply c3d3db7... fixup! Added line 2 with BUG
When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".
Could not apply c3d3db78440e48c1bb637f78e0767520db65ea1e... fixup! Added line 2 with BUG
$ git status
interactive rebase in progress; onto 0ee3343
Last commands done (2 commands done):
pick 62cdd05 Added line 2 with BUG
fixup c3d3db7 fixup! Added line 2 with BUG
Next command to do (1 remaining command):
pick 2b83fe7 Insert 2 --> second line
(use "git rebase --edit-todo" to view and edit)
You are currently rebasing branch 'master' on '0ee3343'.
(fix conflicts and then run "git rebase --continue")
(use "git rebase --skip" to skip this patch)
(use "git rebase --abort" to check out the original branch)
Unmerged paths:
(use "git reset HEAD <file>..." to unstage)
(use "git add <file>..." to mark resolution)
both modified: test.file
no changes added to commit (use "git add" and/or "git commit -a")
$ cat test.file
1
<<<<<<< HEAD
This is a BUG
=======
2
This is NOT a BUG
>>>>>>> c3d3db7... fixup! Added line 2 with BUG
为什么修复程序不能干净地应用？
为什么 fixup 还包含“2”，它不应该在 fixup 引入的补丁中，而是在前一次提交的补丁中。