Fix MacroServer does not exit smoothly after Ctrl+C
#494 (closed) was not completly solved with #510. It was revealed during the Jan18 release tests in https://github.com/sardana-org/sardana/pull/711#issuecomment-369855509.
This is the summary of dependencies versions and the current behavior:
- Taurus 3 and Tango 7 - no problem
- Taurus 4 and Tango 9 - no problem
- Taurus 3 and Tango 8 - MS crash when exiting