keep the mirror hint off forge errors, forward the hyperhive mirror from any controller host

swarm-controller/src/meta_flake.rs

@@ -374,8 +374,7 @@ async fn hyperhive_pin(
     let Some(flake) = committed_flake else {
         let head = forge
             .head_files(HYPERHIVE_OWNER, HYPERHIVE_REPO, None, &[])
-            .await
-            .with_context(missing_hyperhive)?
+            .await?
             .with_context(missing_hyperhive)?;
         return Ok(HyperhivePin {
             rev: head.commit,
@@ -575,6 +574,8 @@ mod tests {
         compares: Mutex<Vec<(String, String)>>,
         /// Every compare fails, as a forge that is down does.
         compare_fails: bool,
+        /// Reads of this `owner/repo` fail, as on a forge that refuses or is down.
+        head_fails: Option<String>,
         /// Every `head_files` read, as `("owner/repo", branch)`.
         head_reads: Mutex<Vec<(String, Option<String>)>>,
     }
@@ -603,6 +604,9 @@ mod tests {
             branch: Option<&str>,
             paths: &[&str],
         ) -> Result<Option<DefaultBranchFiles>> {
+            if self.head_fails.as_deref() == Some(&format!("{owner}/{repo}")) {
+                anyhow::bail!("forge answered 503");
+            }
             self.head_reads
                 .lock()
                 .unwrap()
@@ -874,6 +878,25 @@ mod tests {
         assert!(forge.commits.lock().unwrap().is_empty());
     }
 
+    #[tokio::test]
+    async fn a_forge_error_reading_hyperhive_does_not_carry_the_mirror_hint() {
+        let mut forge = forge_with(&[]);
+        forge.head_fails = Some("hyperhive/hyperhive".to_owned());
+        let err = update(
+            &forge,
+            &FakeLocker::locked(),
+            &settings(),
+            None,
+            &argus_and_reviewer(),
+            &[],
+        )
+        .await
+        .unwrap_err();
+        let err = format!("{err:#}");
+        assert!(err.contains("forge answered 503"), "{err}");
+        assert!(!err.contains("hyperhiveUpstream"), "{err}");
+    }
+
     #[tokio::test]
     async fn a_refused_lock_commits_nothing() {
         let forge = forge_with(&[]);