Extra column when file_name contains an "=" sign, after write_parquet and read_parquet

[PierreOreistein]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

first_df = pl.DataFrame({"col_a": [0, 1, 2], "col_b": ["a", "b", "c"]})
print(first_df)
first_df.write_parquet("data=1.parquet")

second_df = pl.read_parquet("data=1.parquet")
print(second_df)

Log output

No response

Issue description

Context

After saving a file with an equal sign "=", and reloading it, we can observe an extra column.

This issue does not happen when removing the equal sign "=" from the file name.

first_df.write_parquet("data_1.parquet")

second_df = pl.read_parquet("data_1.parquet")
print(second_df)

Expected behavior

No extra column when saving a file with an equal sign.

Installed versions

--------Version info---------
Polars:               0.20.6
Index type:           UInt32
Platform:             Linux-5.4.56.bsk.10-amd64-x86_64-with-glibc2.31
Python:               3.9.18 (main, Jan 26 2024, 14:16:18) 
[GCC 10.2.1 20210110]

----Optional dependencies----
adbc_driver_manager:  <not installed>
cloudpickle:          <not installed>
connectorx:           <not installed>
deltalake:            <not installed>
fsspec:               <not installed>
gevent:               21.12.0
hvplot:               <not installed>
matplotlib:           <not installed>
numpy:                1.26.3
openpyxl:             3.1.2
pandas:               2.2.0
pyarrow:              15.0.0
pydantic:             <not installed>
pyiceberg:            <not installed>
pyxlsb:               <not installed>
sqlalchemy:           <not installed>
xlsx2csv:             <not installed>
xlsxwriter:           <not installed>

[ritchie46]

Set hive_partitioning=False.

EDIT: Hmm.. this should only be triggered by directories, not by filenames.