remove pointless code (closes #17738)
- Issue #17012: shutil.which() no longer fallbacks to the PATH environment
  variable if empty path argument is specified.  Patch by Serhiy Storchaka.
Remove unused import.
Issue #17739: fix the description of SSLSocket.getpeercert(binary_form=True) for server sockets.
Thanks to David D Lowe for reporting.