Extract exception trapping functionality and only invoke it when pdb …

…is not detected to be present. Fixes pypa#9349.

src/pip/_internal/cli/base_command.py

@@ -128,7 +128,7 @@ def _main(self, args):
  # Set verbosity so that it can be used elsewhere.
  self.verbosity = options.verbose - options.quiet
 
- level_number = setup_logging(
+ self.level_number = setup_logging(
  verbosity=self.verbosity,
  no_color=options.no_color,
  user_log_file=options.log,
@@ -186,6 +186,12 @@ def _main(self, args):
  "This will become an error in pip 21.0."
  )
 
+ runner = self.run if 'pdb' in sys.modules else self._trap_run
+ status = runner(options, args)
+ self.handle_pip_version_check(options)
+ return status
+
+ def _trap_run(self, options, args):
  try:
  status = self.run(options, args)
  assert isinstance(status, int)
@@ -210,7 +216,7 @@ def _main(self, args):
  # Bypass our logger and write any remaining messages to stderr
  # because stdout no longer works.
  print('ERROR: Pipe to stdout was broken', file=sys.stderr)
- if level_number <= logging.DEBUG:
+ if self.level_number <= logging.DEBUG:
  traceback.print_exc(file=sys.stderr)
 
  return ERROR
@@ -223,5 +229,3 @@ def _main(self, args):
  logger.critical('Exception:', exc_info=True)
 
  return UNKNOWN_ERROR
- finally:
- self.handle_pip_version_check(options)