"line buffering (buffering=1) isn't supported in binary mode" warnings with Python 3.8

diffoscope-129

$ diffoscope bzip2-1.0.8-3-x86_64.pkg.tar.xz build/bzip2-1.0.8-3-x86_64.pkg.tar.xz 
2019-11-12 23:00:22 W: diffoscope.main: Fuzzy-matching is currently disabled as the "tlsh" module is unavailable.
/usr/lib/python3.8/subprocess.py:844: RuntimeWarning: line buffering (buffering=1) isn't supported in binary mode, the default buffer size will be used
  self.stdout = io.open(c2pread, 'rb', bufsize)
/usr/lib/python3.8/subprocess.py:844: RuntimeWarning: line buffering (buffering=1) isn't supported in binary mode, the default buffer size will be used
  self.stdout = io.open(c2pread, 'rb', bufsize)
/usr/lib/python3.8/subprocess.py:844: RuntimeWarning: line buffering (buffering=1) isn't supported in binary mode, the default buffer size will be used
  self.stdout = io.open(c2pread, 'rb', bufsize)
...