What I have read is that it is only changing the default setting for new repositories, and does not affect existing repositories, and that either way you can still change the default branch name. (I looked, and it also looks like you can now rename any branch easily in GitHub, so maybe that can also help with some things.)
I think that the change is unnecessary, but is probably mostly harmless (although, I do not use git; someone who does might know better than I do).
If you want to import from a different version control system, if it uses a different name such as "trunk", you can keep the same name in a mirror with a different version control system, if that is supported by the system that you are using.
I think that the change is unnecessary, but is probably mostly harmless (although, I do not use git; someone who does might know better than I do).
If you want to import from a different version control system, if it uses a different name such as "trunk", you can keep the same name in a mirror with a different version control system, if that is supported by the system that you are using.