Dual distro support broke "securedrop-admin verify"

[rmol]

Description

When adding support for Focal to the configuration tests in #5529, a check of the MOLECULE_SCENARIO_NAME environment variable broke securedrop-admin verify, where it's not set.

Steps to Reproduce

On an admin workstation:

• Run securedrop-admin setup -t
• Run securedrop-admin verify

Expected Behavior

That the configuration tests would run.

Actual Behavior

You get an error here saying 'NoneType' object has no attribute 'endswith'.

Comments

Should probably check if it's None or just add "" as the default in the os.environ.get call.

[eloquence]

(Added to 1.7.0 milestone, seems like we want a fix in place before QA begins.)