Bug: "git worktree add" Unable to checkout a branch with no local ref

[Alexander Grigoriev]

git version 2.10.2.windows.1:
If a remote branch has never been checked out locally (its ref only exists 
in remotes/<remote>/ directory), "git worktree add" command is unable to 
check it out by its normal short name (not prefixed by remotes/<remote>), 
while "git checkout" command has been able to handle such a branch and 
properly convert it to a local branch.