OMSimulator, SuiteSparse and sundials all have a v3.0.0 tag. Fetching every remote's tags into the shared refs/tags/ let the first one win; the rejected tag objects were still downloaded but unreferenced, so workspaces cloned with --reference borrowed them and gc pruned them two weeks later. The checkout then fails with "fatal: bad object refs/tags/v3.0.0".
Tags now go to refs/tags/<remote>/*, and the cache never prunes, since workspaces depend on every object they borrowed.
