Calling /usr/bin/which isn't possible on Windows. Python 3 has https://docs.python.org/3/library/shutil.html#shutil.which
Created attachment 418906 [details] Patch
Committed r272172: <https://trac.webkit.org/changeset/272172> All reviewed patches have been landed. Closing bug and clearing flags on attachment 418906 [details].
<rdar://problem/73843397>