Tangentally related (the alternative was to start a thread on some
2018-era patch of yours): Is it intentional that when you supply a
gibberish OID or a nonexisting one as an explicit negotiation tip we
don't even warn about it?
Looking at the history of fetch-pack.c I suspect not. It goes back to
ec06283844a (fetch-pack: introduce negotiator API, 2018-06-14), i.e. the
"o && o->type == OBJ_COMMIT" check, now "if (c)" (as in could we look up
a commit) on "master". That in turn seems to go back as far as
9534f40bc42 (Be careful when dereferencing tags., 2005-11-02).
This sounds unintentional, yes. Other than replying to an old email, you
could also write a top-level patch :-)