@dilumaluthge has suggested using "<0.0.1, 1" to support old Julia versions, like in this PR. And that SHA in particular needs "<0.0.1, 0.7, 1".
It seems there was a Pkg bug that has since been fixed which requires this setting, because during testing at different parts in thinks the stdlib versions as v0.0.0 at times, so the package needs to be compatible with v0.0.0 to be loadable.
From my experimenting it seems Julia 1.0 to 1.3 needs this to be able to run tests at all, while some later Julia versions need this (and all their dependencies to have this) only if the test environment is re-resolved by e.g. Pkg.add during the tests.
It’s not clear to me which versions are affected by which version of the bug since there is no issue filed. Although @kristoffer.carlsson said on Slack that the bug is fixed, so that is good at least.