server: skip logging of ECONNRESET

I believe this was exposed by 5492dc20, because the sending of the 500
would have already failed and prevented this logging. On Python 3,
this will be a ConnectionResetError, which is a subtype of OSError,
which is why we check for both OSError and socket.error.

Bonus: this fixes a race in test-hgweb.t where sometimes the
ECONNRESET wouldn't happen, because now we just don't log those
errors.

Differential Revision: https://phab.mercurial-scm.org/D5764

mercurial/hgweb/server.py

@@ -100,9 +100,11 class _httprequesthandler(httpservermod.
     def do_POST(self):
         try:
             self.do_write()
-        except Exception:
+        except Exception as e:
             # I/O below could raise another exception. So log the original
             # exception first to ensure it is recorded.
+            if not (isinstance(e, (OSError, socket.error))
+                    and e.errno == errno.ECONNRESET):
             tb = r"".join(traceback.format_exception(*sys.exc_info()))
             # We need a native-string newline to poke in the log
             # message, because we won't get a newline when using an

tests/test-hgweb.t

@@ -911,18 +911,6 Test signal-safe-lock in web and non-web
 errors
 
   $ cat errors.log | "$PYTHON" $TESTDIR/filtertraceback.py
-  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/?cmd=spam': (glob)
-  Traceback (most recent call last):
-  error: [Errno 104] $ECONNRESET$
-  
-  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/spam': (glob)
-  Traceback (most recent call last):
-  error: [Errno 104] $ECONNRESET$
-  
-  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/spam/tip/foo': (glob)
-  Traceback (most recent call last):
-  error: [Errno 104] $ECONNRESET$
-  
   $ rm -f errors.log
 
 Uncaught exceptions result in a logged error and canned HTTP response