Model.save_base() is called directly when loading fixtures and assumes existing rows will be updated. Branching of "raw" allows to maintain the optimization introduced in #29260 while supporting this edge case. Regression in 85458e94e38c20e57939947ee515a1a53689659f. Thanks Reupen Shah for the report. Backport of 5779cc938a34eb96815c7a40ded2c8f6c8087c58 from master