[Python] Strange decimal cast when allow_decimal_truncate=True

[stevenlandis-rl]

Describe the bug, including details regarding any error messages, version, and platform.

I'm using the python pyarrow module and running into this strange behavior when casting strings into a decimal:

pyarrow.compute.cast(
  pyarrow.array(['0.9999999999999999999999999999999999999999999999999999999999999999999999999']),
  options=pyarrow.compute.CastOptions(
    target_type=pyarrow.decimal128(38, 19),
    allow_decimal_truncate=True
  )
)

""" Returns:
<pyarrow.lib.Decimal128Array object at 0x11878c1c0>
[
  -3711.3482369388076293398
]
"""

Is this behavior expected?

Version: pyarrow==17.0.0

Component(s)

Python