Arduino Nano Clone with CH340: uploading fails with AVR Boards 1.6.21

[sburlot]

Uploading code using Arduino AVR Boards 1.6.21 with Arduino 1.85 on MacOS 10.13.3,
on an Arduino Nano clone with a CH340 chip fails:
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x42
etc..
going back to Arduino AVR Boards 1.6.20 works.
Driver is v1.4 from this page

[per1234]

Closing as duplicate of
arduino/ArduinoCore-avr#593
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