1. A system for supporting patching in a multitenant application server environment, comprising: one or more computers, including an application server environment executing thereon, together with: a plurality of deployable resources, which are used within the application server environment, one or more resource groups, which include groupings of the plurality of deployable resources for use by a partition within a domain, and one or more partitions, wherein each partition of the one or more partitions provides a subdivision of the domain that provides a runtime for use by that partition, and wherein the system associates the one or more partitions and the one or more resource groups with a tenant of the multitenant application server environment for use by the tenant of the multitenant application server environment; and wherein the system uses a patching process that is performed by the application server environment to apply patches to a plurality of servers in the domain in a controlled manner that maintains operations of the domain without interruption, including: applying a patch to create a patched home directory, and performing a rollout of the patched home directory to the plurality of servers in the domain that are to be patched, including for each server of the plurality of servers in the domain to be patched: shutting down the server, updating the server to point to an instance of the patched home directory, restarting a node manager associated with the server so that the server uses the patched home directory, and starting the server.