Git的浅克隆功能
随着Git仓库不断的被修改，整个仓库会变得越来越大，其中最主要的原因是历史提交特别的多，这个对于想立即阅读最新代码或者CI/CD场景下不是特别友好。
面对这种场景，可以利用git提供的浅克隆功能，只clone少部分历史到本地，这样可以极大的减少clone的仓库大小，以PHP源代码代码为例：
目前PHP源码有超过10万个提交，全部clone下来成本不小，如果只是想clone最新的N个提交，可以加上--depth参数：
# git clone https://github.com/php/php-src.git --depth=1 # 1可以换成任意深度，根据需要调整
Cloning into 'php-src'...
remote: Enumerating objects: 18674, done.
remote: Counting objects: 100% (18674/18674), done.
remote: Compressing objects: 100% (16621/16621), done.
remote: Total 18674 (delta 2656), reused 12214 (delta 1882), pack-reused 0
Receiving objects: 100% (18674/18674), 17.71 MiB | 1.25 MiB/s, done.
Resolving deltas: 100% (2656/2656), done.
Checking out files: 100% (18446/18446), done.
但是这样clone下来是没有分支信息的，如果需要看不同分支的代码：
# git remote set-branches origin PHP-7.3.8 # 如果需要全部的分支可以 git remote set-branches origin '*'
# git fetch --depth=1
remote: Enumerating objects: 13268, done.
remote: Counting objects: 100% (13266/13266), done.
remote: Compressing objects: 100% (6744/6744), done.
remote: Total 8549 (delta 5695), reused 4475 (delta 1792), pack-reused 0
Receiving objects: 100% (8549/8549), 6.49 MiB | 693.00 KiB/s, done.
Resolving deltas: 100% (5695/5695), completed with 3878 local objects.
From https://github.com/php/php-src
* branch master -> FETCH_HEAD
* [new branch] PHP-7.3.8 -> origin/PHP-7.3.8
git remote set-branches origin 'PHP-7.3.8'
git fetch --depth=1如果转换成常规克隆，需要使用--unshallow：
# git config remote.origin.fetch '+refs/heads/*:refs/remotes/origin/*'
# git fetch --unshallow
remote: Enumerating objects: 800451, done.
remote: Counting objects: 100% (800446/800446), done.
remote: Compressing objects: 100% (172689/172689), done.
remote: Total 790672 (delta 630180), reused 777010 (delta 616884), pack-reused 0
Receiving objects: 100% (790672/790672), 334.08 MiB | 3.63 MiB/s, done.
Resolving deltas: 100% (630180/630180), completed with 8325 local objects.
From https://github.com/php/php-src
* [new branch] PEAR_1_4DEV -> origin/PEAR_1_4DEV
* [new branch] PECL -> origin/PECL
* [new branch] PECL_4_3 -> origin/PECL_4_3
* [new branch] PECL_OPENSSL -> origin/PECL_OPENSSL
* [new branch] PHAR_1_2 -> origin/PHAR_1_2
* [new branch] PHP-4.0 -> origin/PHP-4.0
* [new branch] PHP-4.0.5 -> origin/PHP-4.0.5
* [new branch] PHP-4.0.6 -> origin/PHP-4.0.6
* [new branch] PHP-4.0.7 -> origin/PHP-4.0.7
* [new branch] PHP-4.2.0 -> origin/PHP-4.2.0
* [new branch] PHP-4.2.2 -> origin/PHP-4.2.2
* [new branch] PHP-4.3 -> origin/PHP-4.3
...