I presume that check-mir is expected to be run on a system with appropriate apt sources enabled. But having the proposed pocket of the development release enabled is not appropriate even on a development system. This means that when a package is blocked from proposed migration, and another package needs to be uploaded to fix it, that second package cannot have "check-mir" run on its source with accurate results, as check-mir is blind to the proposed pocket.
For example: right now, apache2-dev is in saucy-proposed, but there is no such thing in saucy, since it is introduced by apache2 2.4 whose migration is in progress. When I run check-mir on php5 from Debian, I see "apache2-dev does not exist (pure virtual?)" when it does exist in saucy-proposed.
The only way I can think of to fix this is to switch to querying Launchpad directly. Is there any other way?
please reopen if this problem still exists