New download URL :
Due to the death of David Rushby, the creator of kinterbasdb, the project was dormant for some time. Pavel Cisar started a fork which will bring the driver up-to-date with latest Firebird versions. This fork is developed as a subproject of the Firebird project.
Same failure as in #405227
This bug can be closed : kinterbasdb seems to be no longer developed.
Kinterbasdb replacement is fdb (https://bugs.gentoo.org/show_bug.cgi?id=462484)