Merge branch '219-fix-reverseproxy-panics' into 'master'

Don't log http.ErrAbortHandler panics in sentry

Closes #219

See merge request gitlab-org/gitlab-workhorse!392

internal/proxy/proxy.go

@@ -47,5 +47,16 @@ func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		helper.AllowResponseBuffering(w)
 	}
 
+	// If the ultimate client disconnects when the response isn't fully written
+	// to them yet, httputil.ReverseProxy panics with a net/http.ErrAbortHandler
+	// error. We can catch and discard this to keep the error log clean
+	defer func() {
+		if err := recover(); err != nil {
+			if err != http.ErrAbortHandler {
+				panic(err)
+			}
+		}
+	}()
+
 	p.reverseProxy.ServeHTTP(w, &req)
 }