Fixes an issue with Python 3 in MSYS where it fails while trying to join
paths where one part is Unicode (default string on Python3) and the
second part are bytes (returned by the subprocess call).
Closes https://github.com/espressif/esp-idf/issues/5189
As reported on forum:
https://esp32.com/viewtopic.php?f=2&t=13565&p=53476#p53453
split() with no arg will match any whitespace sequence not just
a single space, so takes care of case where two spaces are
inserted in the variable value.