Merge https://github.com/vscosta/yap-6.3

C/c_interface.c

@@ -1781,9 +1781,9 @@ X_API bool YAP_LeaveGoal(bool backtrack, YAP_dogoalinfo *dgi) {
 
   BACKUP_MACHINE_REGS();
   myB = (choiceptr)(LCL0 - dgi->b);
-  if (B > myB) {
+  if (B >= myB) {
     /* someone cut us */
-    return FALSE;
+    return false;
   }
   /* prune away choicepoints */
   if (B != myB) {

C/errors.c

@@ -660,7 +660,7 @@ yamop *Yap_Error__(const char *file, const char *function, int lineno,
   if (LOCAL_DoingUndefp) {
     Yap_PrintWarning(error_t);
   } else {
-    memset(LOCAL_ActiveError, 0, sizeof(*LOCAL_ActiveError));
+    //memset(LOCAL_ActiveError, 0, sizeof(*LOCAL_ActiveError));
     Yap_JumpToEnv(error_t);
   }
   P = (yamop *)FAILCODE;