Fix "Switched to a new branch <name>" to read "Switched to branch
<name>" when <name> corresponds to an existing branch. This bug was
introduced in 02ac983 while introducing the `-B` switch.
Cc: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>