Rearrange series op to be less eager, fixes TimToady's primer

lib/CORE.setting

@@ -2176,8 +2176,11 @@ our sub Niecza::generate-series(@lhs, $rhs, :$exclude-limit) {
     my sub infinite-series (@lhs, $limit ) {
         gather {
             my $i = 0;
-            while @lhs[$i+1].defined { take @lhs[$i]; $i++; } #We blindly take all elems of the LHS except last one.
-            if @lhs[$i] !~~ Code { take @lhs[$i]; $i++; }     #We take the last element only when it is not code
+            # Take all items from the LHS except for terminal Codes
+            # (ordered this way to avoid overeager evaluation)
+            while @lhs[$i] !~~ Code || @lhs[$i+1].defined {
+                take @lhs[$i]; $i++;
+            }
 
             my $next = get-next-closure(@lhs , $limit );
             my $arity = $next.count;