Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
FAILED tests/unit/activation/test_csh.py::test_csh[no_prompt] - UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 99: invalid start byte
FAILED tests/unit/activation/test_csh.py::test_csh[with_prompt] - UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 99: invalid start byte
========== 2 failed, 244 passed, 26 skipped, 59 deselected in 17.50s ===========

Cause: Python's utf-8 decoder encountered a byte (0x92) at position 99 in a file that it couldn't interpret as a valid UTF-8 character.