Clear old Location header (if any) while adding a new one.

This prevents incorrect behaviour when another redirect is issued within
error_page 302 handler.

src/http/modules/ngx_http_static_module.c

@@ -139,6 +139,8 @@ ngx_http_static_handler(ngx_http_request_t *r)
 
         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, log, 0, "http dir");
 
+        ngx_http_clear_location(r);
+
         r->headers_out.location = ngx_palloc(r->pool, sizeof(ngx_table_elt_t));
         if (r->headers_out.location == NULL) {
             return NGX_HTTP_INTERNAL_SERVER_ERROR;

src/http/ngx_http_core_module.c

@@ -983,6 +983,8 @@ ngx_http_core_find_config_phase(ngx_http_request_t *r,
     }
 
     if (rc == NGX_DONE) {
+        ngx_http_clear_location(r);
+
         r->headers_out.location = ngx_list_push(&r->headers_out.headers);
         if (r->headers_out.location == NULL) {
             ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
@@ -1796,6 +1798,8 @@ ngx_http_send_response(ngx_http_request_t *r, ngx_uint_t status,
 
     if (status >= NGX_HTTP_MOVED_PERMANENTLY && status <= NGX_HTTP_SEE_OTHER) {
 
+        ngx_http_clear_location(r);
+
         r->headers_out.location = ngx_list_push(&r->headers_out.headers);
         if (r->headers_out.location == NULL) {
             return NGX_HTTP_INTERNAL_SERVER_ERROR;

src/http/ngx_http_core_module.h

@@ -529,5 +529,12 @@ extern ngx_str_t  ngx_http_core_get_method;
         r->headers_out.last_modified = NULL;                                  \
     }
 
+#define ngx_http_clear_location(r)                                            \
+                                                                              \
+    if (r->headers_out.location) {                                            \
+        r->headers_out.location->hash = 0;                                    \
+        r->headers_out.location = NULL;                                       \
+    }
+
 
 #endif /* _NGX_HTTP_CORE_H_INCLUDED_ */

src/http/ngx_http_script.c

@@ -1106,6 +1106,8 @@ ngx_http_script_regex_end_code(ngx_http_script_engine_t *e)
                           "rewritten redirect: \"%V\"", &e->buf);
         }
 
+        ngx_http_clear_location(r);
+
         r->headers_out.location = ngx_list_push(&r->headers_out.headers);
         if (r->headers_out.location == NULL) {
             e->ip = ngx_http_script_exit;

src/http/ngx_http_special_response.c

@@ -582,6 +582,8 @@ ngx_http_send_error_page(ngx_http_request_t *r, ngx_http_err_page_t *err_page)
     ngx_str_set(&location->key, "Location");
     location->value = uri;
 
+    ngx_http_clear_location(r);
+
     r->headers_out.location = location;
 
     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);