Document a state_contains bug (#1715)

* Document a state_contains bug in the syncer and Inbound

zebrad/src/components/inbound/downloads.rs

@@ -172,6 +172,8 @@ where
 
         let fut = async move {
             // Check if the block is already in the state.
+            // BUG: check if the hash is in any chain (#862).
+            // Depth only checks the main chain.
             match state.oneshot(zs::Request::Depth(hash)).await {
                 Ok(zs::Response::Depth(None)) => Ok(()),
                 Ok(zs::Response::Depth(Some(_))) => Err("already present".into()),

zebrad/src/components/sync.rs

@@ -620,7 +620,8 @@ where
     /// Returns `true` if the hash is present in the state, and `false`
     /// if the hash is not present in the state.
     ///
-    /// TODO: handle multiple tips in the state.
+    /// BUG: check if the hash is in any chain (#862)
+    /// Depth only checks the main chain.
     async fn state_contains(&mut self, hash: block::Hash) -> Result<bool, Report> {
         match self
             .state