Regression caused by cd263b3853482226dbffe99486ff98c8445d6a63

[alexvong243f]

I realize cd263b3 causes a regression because in the following code:

     elseif (isequal (x, []))
      var_pyobj.append (py.list ());

If x is '', we have isequal ('', []) being evaluated to true which is not what we want.

See also the discussion in #1136.

[cbm755]

Is there a particular thing that fails b/c of this? Something like a = pycall_sympy__('return _ins[0]', "")? Or sym('')?

Must be something missing from the test suite anyway: so when we fix this we should add something to the BIST.

[alexvong243f]

Due to this bug,

pycall_sympy__ ('sys.stderr.write(repr(_ins[0]) + "\n")', '');

prints [] rather than ''.

Basically, the empty string turns into the empty list in Python, which is incorrect and different from the old behaviour.