SNOPT tests failing on stable images

[eirikurj]

Description

With changes from PR #364, SNOPT tests are failing on stable images during nightly tests with fStar reported as 0 (see for example here).

Steps to reproduce issue

Any stable image with changes from #364 will generate similar errors as below

Traceback (most recent call last):
  File "/home/mdolabuser/repos/pyoptsparse/tests/test_tp109.py", line 205, in test_autorefine
    self.assert_solution_allclose(sol2, 1e-2)
  File "/home/mdolabuser/repos/pyoptsparse/tests/testing_utils.py", line 123, in assert_solution_allclose
    assert_allclose(sol.fStar, self.fStar[self.sol_index], atol=tol, rtol=tol)
  File "/home/mdolabuser/.pyenv/versions/3.9.16/lib/python3.9/site-packages/numpy/testing/_private/utils.py", line 1530, in assert_allclose
    assert_array_compare(compare, actual, desired, err_msg=str(err_msg),
  File "/home/mdolabuser/.pyenv/versions/3.9.16/lib/python3.9/site-packages/numpy/testing/_private/utils.py", line 844, in assert_array_compare
    raise AssertionError(msg)
AssertionError: 
Not equal to tolerance rtol=0.01, atol=0.01

Mismatched elements: 1 / 1 (100%)
Max absolute difference: 5362.06927538
Max relative difference: 1.
 x: array(0.)
 y: array(5362.069275)

Current behavior

SNOPT tests on stable images are failing

Expected behavior

All tests should pass

Code versions

Any stable image with changes from #364

[eirikurj]

Had a very brief look, and it seems like SNOPT is just returning 0 for obj. Using v7.7.7 on stable works, passing all tests, but v7.7.1 and v7.7.5, fail the tests. Not sure if we want to drop support for SNOPT < v7.7.7 with this version and onwards. In any case, we need to resolve this quickly, as latest and stable images are now inconsistent.

[ewu63]

Oh right, I forgot we were checking older SNOPT versions too. We should probably revert this and only check obj on 7.7.7. I can do this later today if nobody else volunteers.