Summary

ExifTool always outputs JSON in UTF-8 (per RFC 8259), but the exiftool_metadata() function decoded the output using locale.getpreferredencoding(). On systems with non-UTF-8 locale encoding (e.g. Windows with Chinese locale cp936), this caused UnicodeDecodeError when ExifTool returned non-ASCII metadata.

Changes

• _exiftool.py: Replace text=True with encoding=utf-8 in the version-check subprocess call, so stdout is decoded as UTF-8.
• _exiftool.py: Decode JSON output bytes with utf-8 instead of locale.getpreferredencoding().
• _exiftool.py: Remove unused import locale.
• test_module_misc.py: Add test_exiftool_metadata_decodes_utf8 - a mocked unit test that verifies non-ASCII characters are correctly decoded from UTF-8.

Verification

• python -m pytest tests/test_module_misc.py::test_exiftool_metadata_decodes_utf8 -v - PASSED
• python -m pytest tests/test_module_vectors.py -v -x - all 109 PASSED

Backward Compatibility

• No behavior change for UTF-8 locales (the common case)
• Fixes decoding on non-UTF-8 locales (e.g. Windows cp936)
• No new dependencies

Fixes #1972