upload-pack: fix transfer.hiderefs over smart-http

When upload-pack advertises the refs (either for a normal, non-stateless request, or for the initial contact in a stateless one), we call for_each_ref with the send_ref function as its callback. send_ref, in turn, calls mark_our_ref, which checks whether the ref is hidden, and sets OUR_REF or HIDDEN_REF on the object as appropriate. If it is hidden, mark_our_ref also returns "1" to signal send_ref that the ref should not be advertised. If we are not advertising refs, (i.e., the follow-up invocation by an http client to send its "want" lines), we use mark_our_ref directly as a callback to for_each_ref. Its marking does the right thing, but when it then returns "1" to for_each_ref, the latter interprets this as an error and stops iterating. As a result, we skip marking all of the refs that come lexicographically after it. Any "want" lines from the client asking for those objects will fail, as they were not properly marked with OUR_REF. To solve this, we introduce a wrapper callback around mark_our_ref which always returns 0 (even if the ref is hidden, we want to keep iterating). We also tweak the signature of mark_our_ref to exclude unnecessary parameters that were present only to conform to the callback interface. This should make it less likely for somebody to accidentally use it as a callback in the future. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>