Revert ":facepalm:"

This reverts commit e2443305eea560463c273a9fbdf19936b08d91bb.

IPython/core/magics/packaging.py

@@ -12,7 +12,7 b' import re'
 import shlex
 import sys
 from pathlib import Path
-from subprocess import list2cmdline
+from multiprocessing import list2cmdline
 from IPython.core.magic import Magics, magics_class, line_magic