The file name was incorrect, so it was having no effect. Also, the sandbox environment that this was supposed to be ignoring is deprecated. Probably best to just drop it entirely.
This change was introduced in 3bb4e51184066f5cf60daa029c31e7f52398353b, where it was marked as changed due to a typo. However, that is the correct name of this particular virtual environment. See https://hackage.haskell.org/package/virthualenv
The Stackage project provides a cabal.config which locks in a specific
package set. This file should be shared between developers project so
that everyone is developing using the same versions of packages.
