Eryk Sun added the comment:
The behavior in question is documented as follows: "If a component is an
absolute path, all previous components are thrown away and joining continues
from the absolute path component."
In Windows, this is extended to support drives and the six file-path types:
New submission from Bin Hu :
Two root directories shall not be joined in the first place. But, when such a
command is passed, os.path.join() module should give a warning message instead
of just keeping the second argument being passed as the output.
Python 3.7.3 (default, Mar 27 2019,
