Description:
When I mount a FTP server using GNOME Virtual Filesystem and try to copy a file from it, I get the error "cp: error reading /run/user/1000/gvfs/ftp:host=myhost.com/path/to/the/file: Operation not supported".

This error happens on Linux kernel 5.4.arch1-1 and later, but not on 5.3.9.1-1.

I am using the normal "linux" package, not a custom kernel.

Additional info:
I tested with gvfs versions 1.40.2 and 1.42.2 (the latest); the issue repros with both versions on Linux 5.4 and does not repro on either version on Linux 5.3.9.

I *am* able to copy files using Nautilus's copy commands. Maybe Nautilus is using a different sequence of syscalls to copy files?

Steps to reproduce:
1. Use Nautilus to mount an FTP server (click "Other Locations" in the sidebar, then enter server address in bottom bar, and click connect).
2. Open the FTP server's directory in a terminal (right click -> Open in Terminal).
3. Copy a file from the FTP server to somewhere (e.g. cp ./foo ~/).