How does RA handle patched core or modules during the update process?

RA will attempt to apply your patches if they are referenced or placed correctly in your code repository, as described in Patching core and contributed modules. For more information on Drush patching, see Patching and locking modules.

For websites built with Composer, follow the instructions at Patching with Composer to reference all patches either from Drupal.org or a local patches directory above the docroot directory.