regionck.rs: add a delayed_span_bug call to validate an asserrtion
regionck.rs: add a delayed_span_bug call to validate an asserrtion

dwillmer/rust,dwillmer/rust,GBGamer/rust,dwillmer/rust,graydon/rust,dwillmer/rust,GBGamer/rust,dwillmer/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,dwillmer/rust,aidancully/rust,graydon/rust,dwillmer/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,dwillmer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust