When the HostController processes an update to its config, it creates operations to apply the changes to all running servers it is managing, and those get executed as part of the overall operation. The problem is "i1" is not a running server (it isn't started), but the HostController is creating operations for it to add the "env" system property anyway.
The fix for this was committed to the 6.x branch in late May as b05ab00a6fcef99c9d77584b5d8ecd966f80f343. I'm creating the bug for tracking/documentation purposes.
Verified on EAP 6.3.0.ER8