Backport to 2.3:

Backport to 2.3:

If a file is opened with an explicit buffer size >= 1, repeated
close() calls would attempt to free() the buffer already free()ed on
the first close().     [bug introduced with patch #788249]

Making sure that the buffer is free()ed in file object deallocation is
a belt-n-braces bit of insurance against a memory leak.