I wanted to pull commit \"3a2ceef391af73994dfeb0d8ef57ed6a52ef4238\" from branch android. I used the command:
$ git fetch origin 3a2ceef391af73994dfeb0d8ef57ed6a
According to this answer and the given source it looks like BitBucket does not allow you to fetch a commit id, only references.
I cannot say if you can configure this behavior, but I think you can:
git pull origin branchname
git checkout