Windows 7 x64
NodeJS 10.13 x64
UglifyJS 2.3.6

Hello.
While trying to get myself acquainted with source maps I've noticed some strange behaviour of UglifyJS. The options

d:\Work\Web\Projects\Testing\source-maps\js>uglifyjs "d:\Work\Web\Projects\Testing\source-maps\js\scripts\999user-script.js" -o "d:\Work\Web\Projects\Testing\source-maps\js\scripts.js" -c -d DEBUG=false -e jQuery:$ -m -r $,jQuery --source-map scripts.js.map --source-map-root http://192.168.8.128/ -p 5

produce the following scripts.js.map:

{"version":3,"file":"d:\Work\Web\Projects\Testing\source-maps\js\scripts.js","sources":["?"], ... ,"sourceRoot":"http://192.168.8.128/"}

which apparently doesn't work.
So the questions are: is -p option currently supported under Windows? If not, will it be supported?