Intermittent crash of c96.viirs.bnu test; unable to close file on stop

[DavidHuber-NOAA]

The c96.viirs.bnu test failed once, but could not be reproduced after two additional runs. The failure was at the end of the program at line 165 of mtnlm7_oclsm.F.:

forrtl: severe (28): CLOSE error, unit 15, file "Unknown"

This error occurred while regression testing spack-stack/1.6.0 (#844) on Jet. Additional tests on Orion, Hera, and Jet and with the develop branch on Jet did not reproduce the error. Opening this issue for awareness and may close if I cannot recreate the error.