Auto merge of #2931 - Turbo87:auth-user, r=locks
Auto merge of #2931 - Turbo87:auth-user, r=locks

mirage/scenarios/default: Use authenticated session by default

Resolves https://github.com/rust-lang/crates.io/issues/671

r? `@locks`

rust-lang/crates.io,rust-lang/crates.io,rust-lang/crates.io,rust-lang/crates.io