Make sure the changelog mentions files whose flags changed
These changes don't actually need a new filelog entry (see next patch),
but if we don't mention the files in the changelog, it becomes much
harder to find all changesets that touch a file (not even a
"hg log --removed file" will work).
%% Should show unknown
? unknown
removing b
%% Should show unknown and b removed
R b
? unknown
%% Should show a and unknown
a
unknown