Hi Anatoly can you further specify how you want this to work
if the options offered by Bern are not enough?

This seems like a tracker config issue and not something that needs
to be supported by the roundup core.

You could create a "userconfig" class with name and value
string types.

Then:

name = revisionid
value = http://example.site.org/hgview/%s

then in the local replace, open the db, lookup the "revisionid"
object and value. If you see \br[0-9a-f]{6,64}\b in the text,
grab the stuff after the r and format it into the value (url string).

- rouilj