Dev

[mpenkov]

一つのテストが落ちるけど、エンコードに無関係かもしれません。

======================================================================
ERROR: test_dump_and_load_specials (s_test.ExifTests)
test dump and load special types(SingedByte, SiginedShort, DoubleFloat)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "./tests/s_test.py", line 359, in test_dump_and_load_specials
    exif_bytes = piexif.dump(exif_dict)
  File "/Users/misha/git/Piexif/piexif/_dump.py", line 63, in dump
    zeroth_set = _dict_to_bytes(zeroth_ifd, "0th", 0)
  File "/Users/misha/git/Piexif/piexif/_dump.py", line 314, in _dict_to_bytes
    offset)
  File "/Users/misha/git/Piexif/piexif/_dump.py", line 280, in _value_to_bytes
    length_str = struct.pack(">I", length)
UnboundLocalError: local variable 'length' referenced before assignment

[hMatoba]

Thanks.

[coveralls]

Changes Unknown when pulling af8fc2a on mpenkov:dev into ** on hMatoba:dev**.