The following API feature enhancements are available in the 2017.42 release. Dates for preview and production release are the earliest possible release date. Always check your org to verify the release version.
Group Rule evaluation failures are now exposed via the System Log API.
These bug fixes are expected on preview orgs starting October 18, 2017, and on production orgs starting October 24, 2017.
To verify the current release for an org, click the Admin button and check the footer of the Dashboard page.