Check whether we already passed the end.

[[Imported from SVN: r1266]]

dune/istl/interface.hh

@@ -413,7 +413,11 @@ namespace Dune
     const LocalIterator localEnd = send ?  remoteIndices.source_->end() : remoteIndices.target_->end();
     CIter oldremote = remote;
 
-    while(localIndex!=localEnd && !remote.empty()) {
+    if(localIndex==localEnd)
+      //no indices
+      return;
+
+    while(!remote.empty()) {
       if( send ? sourceFlags.contains(localIndex->local().attribute()) :
           destFlags.contains(localIndex->local().attribute()))
       {
@@ -440,7 +444,10 @@ namespace Dune
       }
       typename RemoteIndices::GlobalIndex old=localIndex->global();
       ++localIndex;
+      if(localIndex==localEnd) // no more indices
+        break;
       if(old==localIndex->global())
+        // we have the same global index as the previous one
         remote=oldremote;
     }
   }