builtin/checkout: Fix message when switching to an existing branch

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 02ac9837 while introducing the `-B` switch.

Cc: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/checkout.c

@@ -533,10 +533,13 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 			if (old->path && !strcmp(new->path, old->path))
 				fprintf(stderr, "Already on '%s'\n",
 					new->name);
-			else
+			else if (opts->new_branch)
 				fprintf(stderr, "Switched to%s branch '%s'\n",
 					opts->branch_exists ? " and reset" : " a new",
 					new->name);
+			else
+				fprintf(stderr, "Switched to branch '%s'\n",
+					new->name);
 		}
 		if (old->path && old->name) {
 			char log_file[PATH_MAX], ref_file[PATH_MAX];