sanity: check whether SELF_URL_PATH conforms to data returned by httpd

include/sanity_check.php

@@ -97,14 +97,20 @@
 				}
 			}
 
-			if (SELF_URL_PATH == "http://example.org/tt-rss/") {
-				$urlpath = preg_replace("/\w+\.php$/", "", make_self_url_path());
+			$ref_self_url_path = make_self_url_path();
+            $ref_self_url_path = preg_replace("/\w+\.php$/", "", $ref_self_url_path);
 
+			if (SELF_URL_PATH == "http://example.org/tt-rss/") {
 				array_push($errors,
-						"Please set SELF_URL_PATH to the correct value for your server (possible value: <b>$urlpath</b>)");
+						"Please set SELF_URL_PATH to the correct value for your server (possible value: <b>$ref_self_url_path</b>)");
 			}
 
-			if (!is_writable(ICONS_DIR)) {
+			if (SELF_URL_PATH != $ref_self_url_path && (!defined('_SKIP_SELF_URL_PATH_CHECKS') || !_SKIP_SELF_URL_PATH_CHECKS)) {
+                array_push($errors,
+                    "Please set SELF_URL_PATH to the correct value detected for your server: <b>$ref_self_url_path</b>");
+            }
+
+            if (!is_writable(ICONS_DIR)) {
 				array_push($errors, "ICONS_DIR defined in config.php is not writable (chmod -R 777 ".ICONS_DIR.").\n");
 			}