clang -fsanitize=address breaks initial stream orientation

gistfile1.txt

richard@deodand:~/junk$ cat t.c
#include <stdio.h>
#include <wchar.h>

int main(void) {
  FILE *fp = fopen("/dev/null", "r");
  return printf("initial orientation: %d\n", fwide(fp, 0));
}
richard@deodand:~/junk$ clang-3.6 -fsanitize=address -o t t.c
richard@deodand:~/junk$ ./t
initial orientation: -1
richard@deodand:~/junk$ clang-3.6 -o t t.c
richard@deodand:~/junk$ ./t
initial orientation: 0
richard@deodand:~/junk$ gcc -o t t.c
richard@deodand:~/junk$ ./t
initial orientation: 0