It turns out that all WP_DEBUG_LOG does is:
ini_set( 'log_errors', 1 );
ini_set( 'error_log', WP_CONTENT_DIR . '/debug.log' );
So, if you want to change the log location for WP_DEBUG_LOG in a plugin or theme, webaware’s answer is best. If you just want to have it changed within
wp-config.php you can replace
define( 'WP_DEBUG_LOG', true ); with the above 2 lines and change the log file to wherever you want.
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