1. A system for supporting patching in a multitenant application server environment, comprising: at least one computer and an application server environment executing thereon; a plurality of managed server instances that operate within the application server environment as part of a domain that supports at least one partition or a plurality of partitions, wherein each partition, of the at least one partition or the plurality of partitions, provides a subdivision of the domain that provides a runtime for use by that partition, and wherein the system enables each partition, of the at least one partition or the plurality of partitions, to be associated with a tenant of the multitenant application server environment for use by that tenant; and wherein the system uses a patching process that is performed by the application server environment to update the plurality of managed server instances in a controlled manner that maintains operations of the domain without interruption, including: creating a patched home directory, and performing a rollout of the patched home directory to the plurality of managed server instances, including for each managed server instance of the plurality of managed server instances: shutting down the managed server instance, updating the managed server instance to use an instance of the patched home directory, and restarting the managed server instance to cause the managed server instance to be updated according to the instance of the patched home directory.