unicode-normalization v0.1.10 bumped smallvec to 1, breaking builds with rustc < 1.36. This breaks the expectations that an update using the "caret requirements" will still compile. This notably impacts everyone using rustc as packaged by Debian stable.

To recover, please revert the version bump of smallvec, and release 0.1.12. A clean transition to smallvec 1 can be done in 0.2.0.