hgweb: delete a local variable instead of setting to `None`

The previous code was flagged by PyCharm as an unused variable assignment.

Differential Revision: https://phab.mercurial-scm.org/D7761

mercurial/hgweb/wsgicgi.py

@@ -1,94 +1,94 b''
 # hgweb/wsgicgi.py - CGI->WSGI translator
 #
 # Copyright 2006 Eric Hopper <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 #
 # This was originally copied from the public domain code at
 # http://www.python.org/dev/peps/pep-0333/#the-server-gateway-side
 
 from __future__ import absolute_import
 
 import os
 
 from ..pycompat import getattr
 from .. import pycompat
 
 from ..utils import procutil
 
 from . import common
 
 
 def launch(application):
     procutil.setbinary(procutil.stdin)
     procutil.setbinary(procutil.stdout)
 
     environ = dict(pycompat.iteritems(os.environ))  # re-exports
     environ.setdefault('PATH_INFO', b'')
     if environ.get('SERVER_SOFTWARE', '').startswith('Microsoft-IIS'):
         # IIS includes script_name in PATH_INFO
         scriptname = environ['SCRIPT_NAME']
         if environ['PATH_INFO'].startswith(scriptname):
             environ['PATH_INFO'] = environ['PATH_INFO'][len(scriptname) :]
 
     stdin = procutil.stdin
     if environ.get('HTTP_EXPECT', '').lower() == '100-continue':
         stdin = common.continuereader(stdin, procutil.stdout.write)
 
     environ['wsgi.input'] = stdin
     environ['wsgi.errors'] = procutil.stderr
     environ['wsgi.version'] = (1, 0)
     environ['wsgi.multithread'] = False
     environ['wsgi.multiprocess'] = True
     environ['wsgi.run_once'] = True
 
     if environ.get('HTTPS', 'off').lower() in ('on', '1', 'yes'):
         environ['wsgi.url_scheme'] = 'https'
     else:
         environ['wsgi.url_scheme'] = 'http'
 
     headers_set = []
     headers_sent = []
     out = procutil.stdout
 
     def write(data):
         if not headers_set:
             raise AssertionError(b"write() before start_response()")
 
         elif not headers_sent:
             # Before the first output, send the stored headers
             status, response_headers = headers_sent[:] = headers_set
             out.write(b'Status: %s\r\n' % pycompat.bytesurl(status))
             for hk, hv in response_headers:
                 out.write(
                     b'%s: %s\r\n'
                     % (pycompat.bytesurl(hk), pycompat.bytesurl(hv))
                 )
             out.write(b'\r\n')
 
         out.write(data)
         out.flush()
 
     def start_response(status, response_headers, exc_info=None):
         if exc_info:
             try:
                 if headers_sent:
                     # Re-raise original exception if headers sent
                     raise exc_info[0](exc_info[1], exc_info[2])
             finally:
-                exc_info = None  # avoid dangling circular ref
+                del exc_info  # avoid dangling circular ref
         elif headers_set:
             raise AssertionError(b"Headers already set!")
 
         headers_set[:] = [status, response_headers]
         return write
 
     content = application(environ, start_response)
     try:
         for chunk in content:
             write(chunk)
         if not headers_sent:
             write(b'')  # send headers now if body was empty
     finally:
         getattr(content, 'close', lambda: None)()