Refactor: inline cached_connection (#797)

lib/faraday/adapter/net_http_persistent.rb

@@ -6,16 +6,16 @@ class NetHttpPersistent < NetHttp
       private
 
       def net_http_connection(env)
-        cached_connection do
+        @cached_connection ||=
           if Net::HTTP::Persistent.instance_method(:initialize).parameters.first == [:key, :name]
             Net::HTTP::Persistent.new(name: 'Faraday')
           else
             Net::HTTP::Persistent.new('Faraday')
           end
-        end
+
         proxy_uri = proxy_uri(env)
-        cached_connection.proxy = proxy_uri if cached_connection.proxy_uri != proxy_uri
-        cached_connection
+        @cached_connection.proxy = proxy_uri if @cached_connection.proxy_uri != proxy_uri
+        @cached_connection
       end
 
       def proxy_uri(env)
@@ -61,10 +61,6 @@ def http_set(http, attr, value)
           http.send("#{attr}=", value)
         end
       end
-
-      def cached_connection
-        @cached_connection ||= yield
-      end
     end
   end
 end