tsshd: fix double exit with different exit codes

Signed-off-by: Joonas Loppi <joonas@joonas.fi>

cmd/tsshd/tsshd.go

@@ -157,8 +157,9 @@ func handleSSH(s ssh.Session) {
 		cmd.Process.Kill()
 		if err := cmd.Wait(); err != nil {
 			s.Exit(1)
-		}
+		} else {
 			s.Exit(0)
+		}
 		return
 	}