Incoming zone transfer messages logged to wrong category

BIND 9.15.5 (Development Release) id:87676a6ac0

The following messages appeared in a named log file logging the progress of an incoming zone transfer:

20-Nov-2019 10:45:22.586 general: info: zone example.com/IN/default: Transfer started.
20-Nov-2019 10:45:22.586 xfer-in: info: transfer of 'example.com/IN/default' from 192.168.0.1#53: connected using 192.168.0.2#21522
20-Nov-2019 10:45:32.248 general: info: zone example.com/IN/default: transferred serial 1574275422
20-Nov-2019 10:45:32.248 xfer-in: info: transfer of 'example.com/IN/default' from 192.168.0.1#53: Transfer status: success
20-Nov-2019 10:45:32.249 xfer-in: info: transfer of 'example.com/IN/default' from 192.168.0.1#53: Transfer completed: 7468 messages, 2010931 records, 65913438 bytes, 9.662 secs (6821924 bytes/sec)

(The zone and IP addresses have been anonymised.)

Three of the messages are logged to the xfr-in category and two to the general category. I think that all should be logged to the xfr-in category.

The issue occurs in at least two versions of BIND:

BIND 9.15.5 (Development Release) id:87676a6ac0
BIND 9.11.3-1ubuntu1.8-Ubuntu (Extended Support Version) id:a375815

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