无法使用pip在github上安装特定的git分支 - 权限被拒绝(publickey)

我正在尝试使用pip在Github上安装一个forked repo(https://github.com/theatlantic/django-ckeditor/),但没有成功.

我用的时候

pip install -e git+git://github.com/theatlantic/django-ckeditor.git#egg=django-ckeditor

它确实安装了repo的内容,但是它的旧版本没有我感兴趣的新更改.所以我试图强制pip来获得最新的分支,这显然是atl/4.3.x但我觉得这很奇怪错误,如果分支的名称不正确或类似的东西:

$ pip install -e git+git://github.com/theatlantic/django-ckeditor.git@"atl/4.3.x"#egg=django-ckeditor
Obtaining django-ckeditor from git+git://github.com/theatlantic/django-ckeditor.git@atl/4.3.x#egg=django-ckeditor
  Updating /home/mathx/.virtualenvs/goblets/src/django-ckeditor clone (to atl/4.3.x)
Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
Clone of 'git@github.com:theatlantic/ckeditor-dev.git' into submodule path 'ckeditor/static/ckeditor/ckeditor-dev' failed

我在某个地方犯了错误吗？

谢谢.