Fix bug in the FlatZinc LNS that would cause a crash when the search restarted before finding the first solution

git-svn-id: file:///Users/tack/GecodeGitMigration/gecode-svn-mirror/gecode/trunk@14397 e85b7adc-8362-4630-8c63-7469d557c915

Author: guidotack

changelog.in

@@ -72,6 +72,14 @@ Date: 2015-01-20
 [DESCRIPTION]
 Yada! Yada!
 
+[ENTRY]
+Module: flatzinc
+What:   bug
+Rank:   minor
+Thanks: H�kan Kjellerstrand
+[DESCRIPTION]
+LNS could fail when the search was restarted before finding the first solution.
+
 [ENTRY]
 Module: search
 What:   bug

gecode/flatzinc/flatzinc.cpp

@@ -1613,7 +1613,7 @@ namespace Gecode { namespace FlatZinc {
 
   bool
   FlatZincSpace::slave(const CRI& cri) {
-    if (cri.restart() != 0 && _lns > 0) {
+    if (cri.restart() != 0 && _lns > 0 && cri.last()) {
       const FlatZincSpace& last = static_cast<const FlatZincSpace&>(*cri.last());
       for (unsigned int i=iv_lns.size(); i--;) {
         if ((*_random)(99) <= _lns) {