Hi, on upgrading from buster to backports, I was caught out by the
removal of "certainty" with this opaque message:

    $ lintian
    invalid display constraint = >= pedantic/wild-guess (severity) at /usr/share/lintian/bin/../lib/Lintian/Profile.pm line 835.

I found no reference to wild-guess in the backports man page, so
discovered it was called "certainty" from the buster man page. In
debian/changelog neither of the certainty comments since buster
mentioned its removal, nor were there any active bugs about it.

Gitlab's UI is rubbish for this, so I cloned the repo to discover the
reason for the lack of certainty:

    $ git log -G certainty
    ...
    e1e12f7f4 Use Severity field in tags to determine their disp.. (Felix Lechner,  N, 9 months ago)
              After a discussion in Bug#935706, the old mechanism between tag severity and
              tag certainty that determined the warning level was abandoned.
	      ...
              The old concept of tag certainty no longer exists in Lintian.

It's unfortunate that the good use of gbp dch and a commit title
focussed on the change has ended up hiding the user impact from the
resulting changelog. I considered raising this as a documentation
wishlist bug, so perhaps just include that last commit sentence in the
manpage (which also still mentions "consists of 3 parts" FYI).

However, since I apparently had the below config, lintian displayed the
initial unhelpful error message. I suggest explicity detecting the
certain, possible, wild-guess values and emitting a more user friendly
message to update config or cli parameters.

    $ cat ~/.config/lintian/lintianrc
    display-level = >=pedantic/wild-guess
    display-experimental = true
--
Phil Morrell (emorrp1)