git - 创建 FETCH_HEAD 背后的逻辑

Question

我不明白在某些情况下创建 FETCH_HEAD 背后的逻辑 - 例如:

$ git --version
git version 1.7.2.5

$ git fetch aarep       
From ../aa
 * [new branch]      master     -> aarep/master
 * [new branch]      skin       -> aarep/skin
## Fair enough, creating FETCH_HEADs here wouldn't help


$ git fetch aarep master
From ../aa
 * branch            master     -> FETCH_HEAD
## Instead of creating a remote tracker, git creates a FETCH_HEAD. No problem.

$ git fetch aarep master skin
From ../aa
 * branch            master     -> FETCH_HEAD
 * branch            skin       -> FETCH_HEAD
## What's the point of creating FETCH_HEADs here - only one would survive ?!

Answer 1

在上一个示例之后查看 FETCH_HEAD 的内容。两个 refs 都在那里，可能是这样的:

b0d66b5110faaeb395610ba43b6eb70a18ab5e25        branch 'master' of git://git.kernel.org/pub/scm/git/git
a9004c5cb2204cf950debab328e86de5eefb9da4        branch 'next' of git://git.kernel.org/pub/scm/git/git

它没有被覆盖。

值得一提的是，这是在 git-pull 中使用此功能，它是作为 shell 脚本实现的:

merge_head=$(sed -e '/  not-for-merge   /d' \
    -e 's/  .*//' "$GIT_DIR"/FETCH_HEAD | \
    tr '\012' ' ')