This code (and its other part in TfsChangeset.cs) is here is to detect and prevent the deletion of all the files of the changeset of the current branch which occurs when deleting or renaming (which is a delete + a creation) a branch.
The complete delete of all files make no sense with git and introduce some noise so I preferred to prevent it!
Here is the only way I found to prevent it. It appears more as a workaround as it was one month ago before the refactoring of this part of git-tfs :(

In fact, I detect the delete of the main folder because in this case `change.GitPath` return `string.Empty` and I add a special 'delete change' that permit to detect in TfsChangeset.cs that the changest is a rename changeset.........