checkout: allow dwim for branch creation for "git checkout $branch --"
The "--" notation disambiguates files and branches, but as a side-effect
of the previous implementation, also disabled the branch auto-creation
when $branch does not exist.
A possible scenario is then:
git checkout $branch
=> fails if $branch is both a ref and a file, and suggests --
git checkout $branch --
=> refuses to create the $branch
This patch allows the second form to create $branch, and since the -- is
provided, it does not look for file named $branch.
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>