Comment by g_b

Actually master is used as the default for submodules branch tracking [1]. I maintain a Git client application that deals with submodules & I have to take this use-case into account.

GitHub must work with Git & make this a proper change if they want to do this. Change the submodules specification as well.

[1] https://git-scm.com/docs/gitmodules#Documentation/gitmodules...