Rebase with pygit2

rebase.py

# Purpose: rebase 'other' on top of 'master'
branchc = repo.lookup_branch("other")

branchb = repo.lookup_branch("master")

base = repo.merge_base(branchb.target, branchc.target)
treeb=repo.get(branchb.target).tree

treec=repo.get(branchc.target).tree

base_tree = repo.get(base).tree
repo.checkout(branchb)                       

index=repo.merge_trees(base_tree,treeb,treec)

tree_id = index.write_tree(repo)

repo.create_commit(branchc.name, sig, sig, "blah", tree_id, [branchb.target])
#---------------------------------------------------------------------------
#GitError                                  Traceback (most recent call last)
#<ipython-input-33-f3577ddcf5b0> in <module>()
#----> 1 repo.create_commit(branchc.name, sig, sig, "blah", tree_id, [branchb.target])
#
#GitError: failed to create commit: current tip is not the first parent

since its already committed so its not the parent give the parent if you already committed else leave it blank