refs debug: add a wrapper for "read_symbolic_ref"

In cd475b3b038 (refs: add ability for backends to special-case reading
of symbolic refs, 2022-03-01) when the "read_symbolic_ref" callback
was added we'd fall back on "refs_read_raw_ref" if there wasn't any
backend implementation of "read_symbolic_ref".

As discussed in the preceding commit this would only happen if we were
running the "debug" backend, e.g. in the "setup for ref completion"
test in t9902-completion.sh with:

    GIT_TRACE_REFS=1 git fetch --no-tags other

Let's improve the trace output, but and also eliminate the
now-redundant refs_read_raw_ref() fallback case. As noted in the
preceding commit the "packed" backend will never call
refs_read_symbolic_ref() (nor is it ever going to). For any future
backend such as reftable it's OK to ask that they either implement
this (or a wrapper) themselves.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 12 deletions

diff --git a/refs.c b/refs.c
index 0b79bdd7c3..1a964505f9 100644
--- a/refs.c
+++ b/refs.c
@@ -1676,18 +1676,7 @@ int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
 int refs_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
 			   struct strbuf *referent)
 {
-	struct object_id oid;
-	int ret, failure_errno = 0;
-	unsigned int type = 0;
-
-	if (ref_store->be->read_symbolic_ref)
-		return ref_store->be->read_symbolic_ref(ref_store, refname, referent);
-
-	ret = refs_read_raw_ref(ref_store, refname, &oid, referent, &type, &failure_errno);
-	if (ret || !(type & REF_ISSYMREF))
-		return -1;
-
-	return 0;
+	return ref_store->be->read_symbolic_ref(ref_store, refname, referent);
 }
 
 const char *refs_resolve_ref_unsafe(struct ref_store *refs,