Suppose you have a history containing the three commits A, B and C:

A-B-C

I would like to combine the two commits A and B to one commit AB:

AB-C

I tried

git rebase -i A

which opens up my editor with the following contents:

pick e97a17b B pick asd314f C

I change this to

squash e97a17b B pick asd314f C

Then Git 1.6.0.4 says:

Cannot 'squash' without a previous commit

Is there a way or is this just impossible?