Initialize timezone early

log_event() uses date(), which triggers a PHP notice when the default
timezone has not been set in php.ini (date.timezone) or by the
application.

Since core.php initializes the timezone only after including several
APIs, depending on log and error level settings in config_inc.php, this
can prevent MantisBT from operating properly.

To prevent this problem, we now set the default timezone as early as we
can, and change it later if necessary according to the user's
preferences.

Fixes #22011

core.php

@@ -212,6 +212,14 @@ function __autoload( $p_class ) {
 require_api( 'database_api.php' );
 require_api( 'config_api.php' );
 
+# Set the default timezone
+# To reduce overhead, we assume that the timezone configuration is valid,
+# i.e. it exists in timezone_identifiers_list(). If not, a PHP NOTICE will
+# be raised. Use admin checks to validate configuration.
+@date_default_timezone_set( config_get_global( 'default_timezone' ) );
+$t_tz = @date_default_timezone_get();
+config_set_global( 'default_timezone', $t_tz, true );
+
 if( !defined( 'MANTIS_MAINTENANCE_MODE' ) ) {
 	if( OFF == $g_use_persistent_connections ) {
 		db_connect( config_get_global( 'dsn', false ), $g_hostname, $g_db_username, $g_db_password, $g_database_name, config_get_global( 'db_schema' ) );
@@ -239,25 +247,17 @@ function __autoload( $p_class ) {
 	$g_login_anonymous = true;
 }
 
-# Set the current timezone
 if( !defined( 'MANTIS_MAINTENANCE_MODE' ) ) {
 	require_api( 'authentication_api.php' );
 
-	# To reduce overhead, we assume that the timezone configuration is valid,
-	# i.e. it exists in timezone_identifiers_list(). If not, a PHP NOTICE will
-	# be raised. Use admin checks to validate configuration.
-	@date_default_timezone_set( config_get_global( 'default_timezone' ) );
-	$t_tz = @date_default_timezone_get();
-	config_set_global( 'default_timezone', $t_tz, true );
-
+	# Override the default timezone according to user's preferences
 	if( auth_is_user_authenticated() ) {
-		# Determine the current timezone according to user's preferences
 		require_api( 'user_pref_api.php' );
 		$t_tz = user_pref_get_pref( auth_get_current_user_id(), 'timezone' );
 		@date_default_timezone_set( $t_tz );
 	}
-	unset( $t_tz );
 }
+unset( $t_tz );
 
 # Cache current user's collapse API data
 if( !defined( 'MANTIS_MAINTENANCE_MODE' ) ) {