When using a Python virtualenv, and launching it with a Windows or Windows mixed path (C:\msys64\tmp\virtualenv\bin\python.exe or C:/msys64/tmp/virtualenv/bin/python.exe), sys.prefix would always be returned incorrectly as '/usr'.
When using a Python virtualenv, and launching it with a Windows or Windows mixed path (C:\msys64\tmp\virtualenv\bin\python.exe or C:/msys64/tmp/virtualenv/bin/python.exe), sys.prefix would always be returned incorrectly as '/usr'.