Use distinguishable error messages.

Author: Yasuo Ohgaki

ext/session/session.c

@@ -2074,12 +2074,12 @@ static PHP_FUNCTION(session_regenerate_id)
 	PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
 	if (!PS(id)) {
 		PS(session_status) = php_session_none;
-		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
+		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create new session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
 		RETURN_FALSE;
 	}
 	if (PS(mod)->s_open(&PS(mod_data), PS(save_path), PS(session_name)) == FAILURE) {
 		PS(session_status) = php_session_none;
-		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
+		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create(open) session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
 		RETURN_FALSE;
 	}
 	if (PS(use_strict_mode) && PS(mod)->s_validate_sid &&
@@ -2088,14 +2088,14 @@ static PHP_FUNCTION(session_regenerate_id)
 		PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
 		if (!PS(id)) {
 			PS(session_status) = php_session_none;
-			php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
+			php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create session ID by collision: %s (path: %s)", PS(mod)->s_name, PS(save_path));
 			RETURN_FALSE;
 		}
 	}
 	/* Read is required to make new session data at this point. */
 	if (PS(mod)->s_read(&PS(mod_data), PS(id), &data, PS(gc_maxlifetime)) == FAILURE) {
 		PS(session_status) = php_session_none;
-		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
+		php_error_docref(NULL, E_RECOVERABLE_ERROR, "Failed to create(read) session ID: %s (path: %s)", PS(mod)->s_name, PS(save_path));
 		RETURN_FALSE;
 	}
 	if (data) {