Running any of the following groups of two lines of code will each cause Unity to crash:

UnityEditor.VersionControl.Plugin p = new UnityEditor.VersionControl.Plugin ();
Debug.Log (p.name);

UnityEditor.VersionControl.ConfigField c = new UnityEditor.VersionControl.ConfigField();
Debug.Log (c.name);

UnityEditor.VersionControl.CustomCommand c = new UnityEditor.VersionControl.CustomCommand();
Debug.Log (c.name);

UnityEditor.VersionControl.Message m = new UnityEditor.VersionControl.Message ();
Debug.Log (m.severity);

UnityEditor.VersionControl.Task t = new UnityEditor.VersionControl.Task ();
Debug.Log (t.userIdentifier);

Happens in 5.0 as well, so it's not a regression