AttributeError on serializing database

[thomas-daniels]

Python 3.11.3, on the working branch.

I initially came across this error when running the wikimovies experiment, but it is reproducible with a minimal example:

from tensorlog import comline
db = comline.parseDBSpec("inputs/train-250.cfacts")
db.serialize("test.db")

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/thomas/.local/lib/python3.11/site-packages/tensorlog-1.2.5-py3.11.egg/tensorlog/matrixdb.py", line 314, in serialize
    self.serializeDataTo(os.path.join(direc,"db.mat"))
  File "/home/thomas/.local/lib/python3.11/site-packages/tensorlog-1.2.5-py3.11.egg/tensorlog/matrixdb.py", line 329, in serializeDataTo
    self._saveMatDictWithScipy(fileLike,d)
  File "/home/thomas/.local/lib/python3.11/site-packages/tensorlog-1.2.5-py3.11.egg/tensorlog/matrixdb.py", line 348, in _saveMatDictWithScipy
    scipy.io.savemat(fileLike,d,do_compression=True)
  File "/usr/lib/python3.11/site-packages/scipy/io/matlab/_mio.py", line 300, in savemat
    MW.put_variables(mdict)
  File "/usr/lib/python3.11/site-packages/scipy/io/matlab/_mio5.py", line 884, in put_variables
    self._matrix_writer.write_top(var, name.encode('latin1'), is_global)
                                       ^^^^^^^^^^^
AttributeError: 'tuple' object has no attribute 'encode'

(This also happens with cfacts files that are a lot more trivial than the wikimovies one, so it does not appear to be database-specific.)