hot column causes PSF fit failure

[sbailey]

20200208 exposure 47722 camera b7 had a hot column 2286 (0-indexed) that clobbered fiber 284 causing desi_fit_psf to fail:

desi_psf_fit -a /global/cfs/cdirs/desi/spectro/redux/daily/preproc/20200208/00047722/preproc-b7-00047722.fits --in-psf /global/cfs/cdirs/desi/spectro/redux/daily/exposures/20200208/00047722/shifted-input-psf-b7-00047722.fits --out-psf /global/cfs/cdirs/desi/spectro/redux/daily/exposures/20200208/00047722/fit-psf-b7-00047722_11.fits --first-bundle 11 --last-bundle 11 --first-fiber 275 --last-fiber 299 --broken-fibers 20,87,134,387,414
...
INFO Starting FitSeveralSpots FLUX+TRACE 
WARNING cannot measure flux of spot 25 at x=2285.52 y=1833.73
WARNING cannot measure flux of spot 50 at x=2285.53 y=2036.28
WARNING cannot measure flux of spot 100 at x=2287.14 y=156.461
WARNING cannot measure flux of spot 125 at x=2287.11 y=177.553
WARNING cannot measure flux of spot 150 at x=2287.13 y=163.986
WARNING cannot measure flux of spot 176 at x=2286.28 y=797.35
WARNING cannot measure flux of spot 201 at x=2286.22 y=848.214
WARNING cannot measure flux of spot 253 at x=2285.76 y=1306.39
INFO specex::PSF_Fitter::FitSeveralSpots inc. signal in w=0, npix footprint = 19542
WARNING cholesky_solve failed with status 133
FATAL ERROR (harp) Exception at line 2884 of file specex_psf_fitter.cc:  FitSeveralSpots failed for FLUX+TRACE

Adding 284 to the broken fibers list allowed it to work as a temporary workaround.