literal: remove redundant import
literal: remove redundant import

This appears to be a new warning on Rust nightly.

rust-lang-nursery/regex,rust-lang-nursery/regex,rust-lang-nursery/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang/regex,rust-lang/regex,rust-lang/regex,rust-lang-nursery/regex,rust-lang/regex