clone: support unusual remote ref configurations
When cloning a branchless and tagless but not refless remote using protocol v0 or v1, Git calls transport_fetch_refs() with an empty ref list. This makes the clone fail with the message "remote transport reported error". Git should have refrained from calling transport_fetch_refs(), just like it does in the case that the remote is refless. Therefore, teach Git to do this. In protocol v2, this does not happen because the client passes ref-prefix arguments that filter out non-branches and non-tags in the ref advertisement, making the remote appear empty. Note that this bug concerns logic in builtin/clone.c and only affects cloning, not fetching. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>