When using WinSCP and FileZilla in SFTP, it uses Putty underneath. Putty sends messages ending with @putty.projects.tartarus.org.
More documentation about the meaning of those names can be found at http://tartarus.org/~simon/putty-snapshots/htmldoc/AppendixF.html
This patch accepts theses messages, otherwise a SSH_MSG_CHANNEL_FAILURE is sent to the client and the connection fails.
There is no implementation based on thoses messages in the patch, it just accepts the requests but does not do anything specific about it.