git子模块指定提交

Question

是否可以在.gitmodules文件中指定我要检出的确切提交哈希？我尝试了branch选项

[submodule "mymod"]
    path = mymod
    url = git@github.com:myrepo/mymod.git
    branch = "0123456789abcdef0123456789abcdef01234567"

但出现错误fatal: Needed a single revision