SYMPTOMS:
A file transfer (move) from one NFS-mounted filesystem to another fails with the message

  Error while copying to <dest-path>

  Not on the same file system

while the same file transfer completes successfully in another program, such as 'mc'. The error does not occur when moving within the same NFS-mounted filesystem. The exports on the NFS server are two distinct subtrees, not nested or symlinks.

STEPS TO REPRODUCE:
- Install gnome-commander from git master (1.2.8.5-0ubuntu1 also tested on Ubuntu 10.04).
- Mount two NFS file systems (in my case /c/inbox and /c/share from a Debian-based ReadyNAS)
- Run gnome-commander as a user that has write permissions to both shares.
- Move a file from one share to the other

EXTRA INFORMATION:
Same error occurs with two separate filesystems mounted through a local (loopback) NFS server, e.g., "/tmp 127.0.0.1(rw,sync,no_subtree_check)" and "/home 127.0.0.1(rw,sync,no_subtree_check)".

Debug output in context during the transfer (gnome-commander -d a) of a file named 'ZRLINK.tar.gz':

  [LL] returning from on_dir_list_ok
  [NN] Added monitor to 0x939d0b0 file:///net/inbox
  [FF] refing: 0x0x9379078 ZRLINK.tar.gz to 4
  [KK] FOUND 0x0x939d0b0 file:///net/inbox in the hash-table, reusing it!
  [XX] Starting xfer the file 'ZRLINK.tar.gz' to '/net/inbox'
  [DD] refing: 0x0x939d0b0 inbox to 2
  [FF] un-refing: 0x0x9379078 ZRLINK.tar.gz to 3
  [LL] blocking_list: file:///net/inbox
  [LL] File listing succeded