I'm trying to create a git alias to be able to call `git resquash` from `foo` branch (a child of `master`). The idea is to do a `git rebase -i` from the first commit in that branch without knowing the commit. Something is wrong though. I keep getting errors when trying it out.

Maybe my expansions are wrong? I'm using ZSH. 

```
resquash = f() { CURRENTBRANCH=$(git symbolic-ref --short HEAD) ;\                      
                 COMMONCOMMIT=$(git merge-base ${CURRENTBRANCH} ${1-master}) ;\                      
                 git rebase -i $COMMONCOMMIT }; f

```