The pull request scenario is what scares me. Someone sends you a drive by pull request that has a ton of changes and you don't notice they slipped an obfuscated bash quirk into the .envrc (along with legitimate changes to the file) that invokes their obfuscated nasty script. You pull down the change, approve the envrc (looks fine!), and poof there goes your home directory or worse.

The same goes for your unit tests or just the application itself though