simple use case advice

[Chris Hecker]

I've got a branch, and version N works, and version N+1 doesn't.  I 
already checked in N+1.  In the old days, I'd roll back to N, keeping a 
separate manual copy of N+1, and do the binary search thing, then sync 
to N+1 and fix the problem.

Is there a fancy dvcs way to make this easier?  Should I just make a new 
branch at N, then do the work there, checking in, until it's N+1+bugfix, 
then merge that over to the main branch?

Hopefully that makes sense.

Chris