Check that a mirror write returning an error will cause a reconnect and retry

tests/fakes/dest/hang_after_write.rb

@@ -6,22 +6,23 @@
 # write has gone MIA, and we expect a reconnect.
 
 require 'flexnbd/fake_dest'
-include FlexNBD::FakeDest
+include FlexNBD
 
-sock = serve( *ARGV )
-client_sock1 = accept( sock )
-write_hello( client_sock1 )
-read_request( client_sock1 )
+server = FakeDest.new( *ARGV )
+client1 = server.accept( server )
+client1.write_hello
+client1.read_request
 
 t = Thread.start do
-  client_sock2 = accept( sock, "Timed out waiting for a reconnection",
+  client2 = server.accept( "Timed out waiting for a reconnection",
                         FlexNBD::MS_REQUEST_LIMIT_SECS + 2 )
-  client_sock2.close
+  client2.close
 end
 
 sleep( FlexNBD::MS_REQUEST_LIMIT_SECS + 2 )
-client_sock1.close
+client1.close
 
 t.join
 
+server.close
 exit(0)