如何不弹出这个文件？

Question

git pull origin master --allow-unrelated-histories
上面的命令运行时，将弹出一个vim编辑窗口，出现下面的文字

1 Merge branch 'master' of https://github.com/xxxx/mytest
2
3 # Please enter a commit message to explain why this merge is necessary,
4 # especially if it merges an updated upstream into a topic branch.
5 #
6 # Lines starting with '#' will be ignored, and an empty message aborts
7 # the commit.

请问，如何不让这个窗口弹出？