For 12.6 and 13.0 the answer is that Windows 10 is supported. Rose Sakach posted this update on the Communities website on this thread: https://communities.ca.com/ideas/235728932
Rose Sakach Apr 28, 2016 9:36 AM
We are planning to certify Windows 10 with CA Harvest SCM V13 over the course of our incremental delivery.
We are aware of several customers using Windows 10 with CA Harvest SCM r12.6 (Client and Agent) with no issues. CA Harvest SCM r12.6 and V13 are supported with Windows 10.
Please use this thread to indicate any further requirements for this certification.
Later in that thread, and in a separate thread, Kola Lakshmi provided the following update about V13:
Lakshmi Kola Oct 7, 2016 1:14 AM
Windows 10 certification is complete in the first increment release of V13 base version release. Please plan your upgrade in order to leverage this.
Please refer the following support page in the CA Support site for more details:
For SCM 12.5, though it’s officially no longer supported, we have not had any reports of problems with Windows 10, so it should work just fine as well.