btrfsctl -a doesn't find my btrfs

If I scan I device with a btrfs with -A, it finds it:

(~/btrfs-progs-unstable) sudo ./btrfsctl -A /dev/sda5 operation complete
Btrfs v0.19-1-g4f89b6e-dirty

But when I do a "scan all devices", it can't find my btrfs on /dev/sda5:

(~/btrfs-progs-unstable) sudo ./btrfsctl -a
Scanning for Btrfs filesystems
failed to read /dev/sr0

I'm using btrfs-progs-unstable version 4f89b6eb0718ade63152791db32794da78fbba70. Am I doing something wrong or misinterpreting how btrfsctl works?

I notice that "-a" does a:

ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
&num_devices,

              BTRFS_SUPER_INFO_OFFSET);

Whereas "-A" does a:

    fd = open("/dev/btrfs-control", O_RDWR);
    if (fd < 0) {
      perror("failed to open /dev/btrfs-control");
      exit(1);
    }

Followed by a:

ret = ioctl(fd, BTRFS_IOC_SCAN_DEV, &args);

Should "-a" be taught to follow "-A"? I could make a patch if so...

jr