install 2.0 with pipeline but no Subvwersion.
Restart Jenkins
Logs contian the following Warning
Mar 31, 2016 5:58:34 PM hudson.ExtensionFinder$GuiceFinder$FaultTolerantScope$1 error WARNING: Failed to instantiate optional component org.jenkinsci.plugins.workflow.steps.scm.SubversionStep$DescriptorImpl; skipping
But that's really OK as the extension is optional - so does not need to be at WARNING level.
danielbeck says Jenkins logs warnings if an option extension cannot be loaded. Could be changed to not log anything, but not sure that's a good idea.