Fossil SCM

I had some checkin (A) that introduced a bad change.

Then trying to fix it, I made a new checkin (B) with some changes in the lines introduced in (A).

When I saw that the change B was not improving the situation... I decided to run "fossil merge --backout A". It took away all the lines introduced by A, but it did not say anything, that the lines in the working directory were not exactly those introduced by A.

Shouldn't it say, that the change A cannot be backed out directly, as it has conflicts introduced by B?