GsFile >> flush may incorrectly appear to succeed on disk full from Linux
For sessions running on Linux, a GsFile >> flush may not return nil (implying
that the flush succeed), when the flush did not occur and no bytes were
written to disk. This is the case if the target instance of GsFile is
open on a disk that is full, and cannot be written to.
This is an error in the Linux operating system call fflush().
The GsFile >> close method will error if the disk is full. Note bug 40382,
which will result in gem crash on logout. Carefully avoid disk full conditions
on Linux in versions of the server that are subject to bug 40382.