My suggestion was that whoever invented Python was a C coder and used the similar convention from that language.
But it is not a similar convention. ** in C and ** in Python are completely different things, not even slightly related. I'm sure Guido van Rossum did some C programming in his days, but Python was mostly influenced by a language called ABC, not by C.
Anyhow, this is getting very offtopic.
chasing solution, I found that number of ppl write that setDTR(False) could be called according to documentation but that it does not work .. someone say it's bug in python some that it serial library some ... irrelevant it does not seems to be working 
...
what I found that works is before you open port with serial library
f = open(port)
attrs = termios.tcgetattr(f)
attrs[2] = attrs[2] & ~termios.HUPCL
termios.tcsetattr(f, termios.TCSAFLUSH, attrs)
f.close()
but this really does exactly the same thing I'm doing in udev rules with stty .. is this something octoprint should be doing, I don't know ... this is not "how it opens a port" it changes a property of the port itself (after this any other app opening that port will not be able to use DTR .. so for e.g. a plugin that updates the firmware will fail)