PyDMLineEdits past the pv into themselves when trying to copy a pv out of them

[Ryan-McClanahan]

Describe the bug

PVs can be copied out of a widget using middle click. When using this feature with a line edit the PV gets pasted into the PyDMLineEdit widget upon releasing middle click. Clicking away from the PyDMLineEdit does clear the pasted PV. But it would be nice to not paste the PV in the first place.

before middle click after releasing middle click after clicking away from the widget