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

tests/fakes/dest/error_on_write.rb

@@ -0,0 +1,21 @@
+#!/usr/bin/env ruby
+# encoding: utf-8
+
+require 'flexnbd/fake_dest'
+include FlexNBD
+
+server = FakeDest.new( *ARGV )
+client = server.accept
+
+client.write_hello
+handle = client.read_request[:handle]
+client.write_error( handle )
+
+
+client2 = server.accept( "Timed out waiting for a reconnection" )
+
+client.close
+client2.close
+server.close
+
+exit(0)