Loading EXIF data for TIFF files throws exception

[gkyle]

Example exception:

+--------+------------+-------+-------+------------------------+
| Offset | Access | Value | Bytes | Format |
+--------+------------+-------+-------+------------------------+
| | | | | TiffHeader (Structure) |
| 0 | byte_order | 12617 | 31 49 | tiff_byte_order |
+--------+------------+-------+-------+------------------------+

ValueError occurred during unpack operation:

12617 is not a valid TiffByteOrder

This happens at during EXIF processing in exif module. I've had issues using this module for TIFF images in other projects.