fix: an answer whose client went away ends quietly, and a shell whose client left before it opened is stopped.

debian-package/src/usr/lib/vpn-router/metrics

@@ -405,15 +405,19 @@ class Handler(BaseHTTPRequestHandler):
                     registry = CollectorRegistry()
                     registry.register(Sample(current))
                     body, kind, code = generate_latest(registry), CONTENT_TYPE_LATEST, 200
-        self.send_response(code)
-        self.send_header('Content-Type', kind)
-        self.send_header('Content-Length', str(len(body)))
-        self.send_header('Cache-Control', 'no-store')
-        for name, value in extra:
-            self.send_header(name, value)
-        self.end_headers()
-        if send_body:
-            self.wfile.write(body)
+        try:
+            self.send_response(code)
+            self.send_header('Content-Type', kind)
+            self.send_header('Content-Length', str(len(body)))
+            self.send_header('Cache-Control', 'no-store')
+            for name, value in extra:
+                self.send_header(name, value)
+            self.end_headers()
+            if send_body:
+                self.wfile.write(body)
+        except ConnectionError:
+            # The client went away before the answer was written.
+            self.close_connection = True
 
     def do_GET(self):
         self.answer(True)