Comment 3 for bug 545790

I think it is a dpkg bug that this error message does not explain what is going on. The sequence of events is:

1. write() something to stdout
2. fflush(stdout)
3. check ferror(stdout) and display an error message based on the value of errno

If write() returns an error, but fflush() does not (because there is nothing left in the buffer?), then we end up with this "Success" result (and the actual error code is lost)