ltl2ta: fix a crash with --ta.

* src/taalgos/tgba2ta.cc: Do not assume the input is an sba.
* src/tgbatest/ltl2ta2.test: New file.
* src/tgbatest/Makefile.am: Add it.
* NEWS: Mention the fix.

src/tgbatest/Makefile.am

@@ -96,6 +96,7 @@ TESTS = \
   ltl2neverclaim.test \
   ltl2neverclaim-lbtt.test \
   ltl2ta.test \
+  ltl2ta2.test \
   ltlprod.test \
   bddprod.test \
   explprod.test \

src/tgbatest/ltl2ta2.test

@@ -0,0 +1,27 @@
+#!/bin/sh
+# Copyright (C) 2014 Laboratoire de Recherche et Développement de
+# l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+. ./defs
+
+set -e
+
+# This used to trigger an assert because of BA simulation not
+# returning an instance of spot::sba.
+run 0 ../../bin/ltl2tgta --ta 'G(F(a U b) U (c M d))'