Impossible to change group id when artifact deployed using sftp.

We should have fine grained access to files in our central repository for groups of developers. When I try to use this feature then error occured - sftp cannot change the group ownership.

SFtpDeployer.java, Line 189:
request.getDestFile() returns file with path from repository root.
// channel.chgrp(groupId.intValue(), request.getDestFile());
channel.chgrp(groupId.intValue(), request.filename());