Github上fork别人的项目之后有时候希望与上游的源码保持一致，同时远程分支也需要进行维护。
克隆项目到本地
虽然github也提供在线编辑功能，但是一般还是拉回本地更方便。这里以weld-core项目为例：
[edony@edony coding:167]$ git clone git@github.com:edonyM/python-patterns.git Cloning into 'python-patterns'... remote: Counting objects: 636, done. remote: Total 636 (delta 0), reused 0 (delta 0), pack-reused 636 Receiving objects: 100% (636/636), 134.75 KiB | 29.00 KiB/s, done. Resolving deltas: 100% (381/381), done.
设置上游远程仓库
当成功fork一个项目后，无论你怎么修改fork出来的项目，原来的项目（github叫做upstream，一般译作上游项目）是不会受到影响的，这在上游项目来说自然是极好的保护，但是，fork出来的项目如何能够及时反映上游项目的变更呢？这就首先需要设置本地项目的“远程仓库”属性，即告诉git命令，本地项目的上游项目是谁。比如针对weld-core项目，
git remote add upstream https://github.com/faif/python-patterns.git
设置好远程仓库后，可以检查一下：
[edony@edony python-patterns:172]$ git remote -v origin git@github.com:edonyM/python-patterns.git (fetch) origin git@github.com:edonyM/python-patterns.git (push) upstream https://github.com/faif/python-patterns.git (fetch) upstream https://github.com/faif/python-patterns.git (push)
现在，本地仓库有了两个远程仓库：
- origin: 这是fork出来的仓库
- upstream: 这是上游项目的仓库
同步远程仓库
设置好上游远程仓库后，将上游远程仓库的最新变化更新到本地。我这边的情况是很久没有和上游项目同步了，因此更新下来的内容比较多：
[edony@edony python-patterns:173]$ git fetch upstream remote: Counting objects: 614, done. remote: Compressing objects: 100% (19/19), done. remote: Total 614 (delta 158), reused 155 (delta 155), pack-reused 440 Receiving objects: 100% (614/614), 217.50 KiB | 75.00 KiB/s, done. Resolving deltas: 100% (353/353), completed with 31 local objects. From https://github.com/faif/python-patterns * [new branch] master -> upstream/master
设置本地分支
首先查看一下当前有哪些分支：
[edony@edony python-patterns:174]$ git branch -a * master remotes/origin/HEAD -> origin/master remotes/origin/master remotes/upstream/master
要确保本地代码的分支（branch）设置合适，一般设置为master：
git checkout master
合并上游项目和本地项目
既然本地分支设置为master，有必要将上游项目的master和本地的master合并，也就是上游项目的最新变化融合到本地：
[edony@edony python-patterns:175]$ git merge upstream/master Updating 18a6cd2..8414931 Fast-forward .travis.yml | 34 ++++++++++++++++++ README.md | 90 ++++++++++++++++++++++++++++++----------------- behavioral/__init__.py | 0 behavioral/catalog.py | 177 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ chain.py => behavioral/chain.py | 51 ++++++++++++++++++--------- chaining_method.py => behavioral/chaining_method.py | 4 +++ behavioral/command.py | 57 ++++++++++++++++++++++++++++++ iterator.py => behavioral/iterator.py | 8 ++--- mediator.py => behavioral/mediator.py | 1 - memento.py => behavioral/memento.py | 16 +++++----
提交本地变更，更新origin仓库
本地的变更需要git push回origin：
[edony@edony python-patterns:176]$ git push origin master Counting objects: 614, done. Delta compression using up to 8 threads. Compressing objects: 100% (287/287), done. Writing objects: 100% (614/614), 218.72 KiB | 0 bytes/s, done. Total 614 (delta 341), reused 586 (delta 326) remote: Resolving deltas: 100% (341/341), completed with 14 local objects. To github.com:edonyM/python-patterns.git 18a6cd2..8414931 master -> master
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