Merge of r4473: Core: protection from cycles with named locations and post_action. Now redirects to named locations are counted against normal uri changes limit, and post_action respects this limit as well. As a result at least the following (bad) configurations no longer trigger infinite cycles: 1. Post action which recursively triggers post action: location / { post_action /index.html; } 2. Post action pointing to nonexistent named location: location / { post_action @nonexistent; } 3. Recursive error page for 500 (Internal Server Error) pointing to a nonexistent named location: location / { recursive_error_pages on; error_page 500 @nonexistent; return 500; }