As of 3.1.6, glue record A names in the recursor's custom hint-file are not recognized unless the entry ends with a dot. This was noted when a 3.1.4 -> 3.1.7 failed due to it being unable to properly handle the existing file.
In this situation the server attempts to start, but complains that it has no glue for the configured NS records. A rec-control cache dump shows that these dot-less entries get loaded, but have two dots appended to the name.
This appears to just affect RR names, not RR data.
Fixed in commit 1458