batch_process() throws "Route required" when the request has no matched route

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Problem/Motivation

batch_process() builds source_url with Url::fromRouteMatch(\Drupal::routeMatch()). A request from a dr console command has no matched route. The call throws InvalidArgumentException: Route required. Each console command that runs a batch must first set the <none> route on the request, as KernelTestBase does.

Steps to reproduce

Push an unrouted request on the request stack. Call batch_set(), set progressive to FALSE, then call batch_process().

Proposed resolution

batch_process() uses the <none> route for source_url when the route match has no route object. _batch_finished() reads source_url only for progressive batches. Non-progressive batches are not affected by the value.