fetch/transport/ls_refs: Post-filter of references

The Git protocol specification states about `ls-refs`[^1]:

>    ref-prefix <prefix>
> When specified, only references having a prefix matching one of
> the provided prefixes are displayed. Multiple instances may be
> given, in which case references matching any prefix will be
> shown. Note that this is purely for optimization; a server MAY
> show refs not matching the prefix if it chooses, and clients
> should filter the result themselves.

The `ref-prefix` arguments should not be relied on and post-filtering
after the ls-refs invocation should also be performed.

[^1]: https://git-scm.com/docs/protocol-v2#_ls_refs

crates/radicle-fetch/src/transport/ls_refs.rs

@@ -67,5 +67,19 @@ where
         false, /* trace packetlines */
     )?;
 
+    // Even though we sent `ref-prefix`, listed refs must still be
+    // filtered, since `ref-prefix` is just an optimization hint.
+    // See <https://git-scm.com/docs/protocol-v2#_ls_refs>.
+    let refs = refs
+        .into_iter()
+        .filter(|r| {
+            let (refname, _, _) = r.unpack();
+            config
+                .prefixes
+                .iter()
+                .any(|prefix| refname.starts_with(prefix))
+        })
+        .collect();
+
     Ok(refs)
 }