In the 423/435 stream devices, dev.copy() was moved back to the main process.

[santorofer]

The 423/435 streaming devices contain a call to copy the tree (dev.copy()) inside the MDSWorker's new thread. This breaks the code when executing it from an mdsip service (i.e. when dispatching the INIT action). Moving that statement back to the main process thread fixes the issue.