Some old packages build on 1st May, 2018 with version 4.6.0-preview3-26501-xx cause several problems during testing. In CoreCLR repo tests are build and run in many cases against not latest 4.6.0-preview1-xxxxx-xx packages but 4.6.0-preview3-26501-xx packages. It is possible to manually compensate for that problem but it may pop up in many different situations as well.

My proposal is to delete all 4.6.0-preview3-26501-xx from all feeds to solve this issue permanently.