Ghostscript execution fails on Windows 10

[r4ph43l-GitHub]

Just encountered an issue running pypdfocr on Windows 10.

Ghostscript, being installed on Windows 10 by default into "C:\Program Files\gs\gs9.21\bin\gswin64c.exe" fails execution using subprocess.check_output command in pypdfocr_gs.PyGs._run_gs.

The execution on a cmd line of the complete same command works.

[r4ph43l-GitHub]

Seems not to be the first appearance of this issue:
https://stackoverflow.com/questions/30014607/command-program-not-executing-from-python-subprocess

unfortunately neither putting ghostscript binary directory inside path environment nor using string escaping works. After putting gs-bin directory into the path environment, the error I get is
"The syntax for the filename, directoryname or drive description is wrong"
"The filename, directory name, or volume label syntax is incorrect"
resulting in an
"ERROR: Ghostscript execution failed"