The git bisect start step gives the confused state, that I am pretty sure is a kernel.org kernel, which wouldn't have the ./debian/rules file and needs to be compiled via different methods (not working for me). However, if you just tell it "git bisect good", it will proceed to the next step, and the ./debian/rules file will be there. If that could be made to compile, then contining should be possible. Yes, it is unclear if that is the actual correct direction to proceed, but it wouldn't take long to try the end points (i.e. good, good, good ... from this point only building the last one and bad, bad, bad... from the same point, only building the last one)
Edit: As a sanity check I downloaded and compiled 3.2.0-32.51, the current 12.04 kernel. It compiled fine, although it took a few minutes longer than in the past.