Fix keyerror when merging certain branching structures

Signed-off-by: Jacob Stopak <jacob@initialcommit.io>

Author: initialcommit-io

git_sim/git_sim_merge.py

@@ -65,6 +65,7 @@ def execute(self):
         else:
             self.get_commits()
             self.parse_commits(self.commits[0])
+            self.i = 0
             self.get_commits(start=self.scene.args.branch[0])
             self.parse_commits(self.commits[0], shift=4*m.DOWN)
             self.center_frame_on_commit(self.orig_commits[0])