Fixing a valgrind warning introduced in the previous changeset:

"have_warnings" was set to an uninialized value when converting
a negative number to datetime.

sql/time.cc

@@ -303,9 +303,16 @@ static bool number_to_time_with_warn(bool neg, ulonglong nr, ulong sec_part,
   else
   {
     f_type= MYSQL_TYPE_DATETIME;
-    res= neg ? -1 : number_to_datetime(nr, sec_part, ltime, fuzzydate, &was_cut);
+    if (neg)
+    {
+      res= -1;
+    }
+    else
+    {
+      res= number_to_datetime(nr, sec_part, ltime, fuzzydate, &was_cut);
       have_warnings= was_cut && (fuzzydate & TIME_NO_ZERO_IN_DATE);
     }
+  }
 
   if (res < 0 || have_warnings)
   {