Merge branch '2270-bad-value-in-images-txt-release-artifact' into 'master'

Resolve "bad value in images.txt release artifact"

Closes #2270

See merge request !4900

tests/images.txt

-registry:2
 registry1.dso.mil/ironbank/big-bang/base:2.1.0
 registry1.dso.mil/ironbank/big-bang/utilities:1.0.3
 registry1.dso.mil/ironbank/opensource/kubernetes-1.21/kubectl:v1.21.14