fopen with "a+" does not respect setting file read position to start of file

[Brebner, Gavin]

We hit a problem in a code, and narrowed it down to a test case that does :

  while (cnt) {
    f=fopen(host_file, "a+");
    if (!f)
      perror("dup_host_file: Could not open hostfile");
    /* rewind(f); */
    while (cnt) {
      int ret=fscanf(f, "%s", line);
      if (ret != EOF) {
	  fprintf(f, "%s\n", line);
	  cnt--;
	  dup++;
	}
    }
    fclose(f);

In earlier versions of cygwin we have, this works fine, however in the recently installed 
versions, it no longer works. It seems that fopen(host_file, "a+") is NOT positioning the
read position at the start of the file as it should. Adding an explicit rewind(f) is a 
work around.

Gavin


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