Based on what is written on the homepage of the project, the most recent version of this packages supports Berkeley DB 4.7, 4.8, 5.1, 5.3, 6.1 and 6.2, which suggests that the COMMENT variable should be updated.
A commit references this bug:
Date: Tue Apr 24 00:04:11 UTC 2018
New revision: 468151
databases/py-bsddb3: Fix COMMENT
Submitted by: 0mp