Return buffer stream to beginning for exception handling.

Author: smlindauer

src/sasctl/_services/model_repository.py

@@ -432,6 +432,8 @@ def add_model_content(cls, model, file, name, content_type="multipart/form-data"
                 for item in model_contents:
                     if item.name == name:
                         cls.delete("/models/{}/contents/{}".format(id_, item.id))
+                        # Move IO buffer back to start
+                        files["files"][1].seek(0)
                         return cls.post(
                             "/models/{}/contents".format(id_),
                             files=files,