I'm interested in this story because Rust is a language that does intend to follow semver, which AFAIK is something that has never been attempted by a programming language. As of yet it hasn't been forced to bump versions thanks to clauses 4 and 9 of the semver spec, but that will change as of the 1.0.0 release on May 15. Before that date I highly anticipate a document from the Rust developers that will attempt to lay out precisely what does and does not constitute a "breaking change" in order to avert the situation that has arisen here.
