Investigate failed weekly 2022-01-02

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FAIL: testResiduals (__main__.ArcTestCase_brn_39) (arm='b', fiberId=2)
Test that wavelength fit residuals are reasonable
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Traceback (most recent call last):
 File "/scratch/pprice/jenkins/weekly/2022-01-02/build/stack/miniconda3-4.5.12-1172c30/Linux64/pfs_pipe2d/w.2022.01/python/pfs/pipe2d/weekly/test_weekly.py", line 139, in testResiduals
   self.assertFloatsAlmostEqual(robustRms, 0.0, atol=atol)
 File "/scratch/pprice/jenkins/weekly/2022-01-02/build/stack/miniconda3-4.5.12-1172c30/Linux64/utils/18.1.0/python/lsst/utils/tests.py", line 735, in assertFloatsAlmostEqual
   testCase.assertFalse(failed, msg="\n".join(errMsg))
AssertionError: True is not false : 0.079973473945946 != 0.0; diff=0.079973473945946/0.079973473945946=1.0 with rtol=2.220446049250313e-16, atol=0.05