Amanda amlabel CURL error: SSL certificate problem when using S3 buckets

This one was fun. Issue The error presented when attempting to label S3 buckets for use by Amanda in a virtual tape changer configuration. The OS is Linux and the distribution, Gentoo. The exact error encountered was labeling tape in slot 1 (s3:myBucket/backupSet/0001/): Reading label... While trying to read tapestart header: CURL error: SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed (CURLcode 60) Reading the tape label failed: Error was Device error. »