描述
在使用git pull origin master拉取github代码时，报以下错误：
fatal: refusing to merge unrelated histories
解决办法
将git pull origin master换成git pull origin master --allow-unrelated-histories。
本人之所以还有错误，是因为有冲突，解决后commit一下即可。
原因
以下说明来自Stack Overflow，英文不太行，有兴趣自己研究一下咯。
“git merge” used to allow merging two branches that have no common base by default, which led to a brand new history of an existing project created and then get pulled by an unsuspecting maintainer, which allowed an unnecessary parallel history merged into the existing project. The command has been taught not to allow this by default, with an escape hatch –allow-unrelated-histories option to be used in a rare event that merges histories of two projects that started their lives independently.