Bottle does not correctly render IPv6 addresses in startup prints

[heliosfa]

When Bottle v0.12.25 starts up, it does not correctly render IPv6 addresses in it's startup blurb.
It fails to enclose a raw IPv6 address in square brackets, making the listening address presented invalid.

Minimum reproducible example:

#!/usr/bin/python3
from bottle import route, run
run(host='::1')

Actual output:

Bottle v0.12.25 server starting up (using WSGIRefServer())...
Listening on http://::1:8080/
Hit Ctrl-C to quit.

Expected Output:

Bottle v0.12.25 server starting up (using WSGIRefServer())...
Listening on http://[::1]:8080/
Hit Ctrl-C to quit.

(note the square brackets around "::1").