Fix another stall bug

If a task fails to get marked as failed (for whatever reason), we still want to
delete it from the task graph. Otherwise it'll get left in the task graph and
we'll eventually block on its completion (it's marked as running).

Author: Mark-Simulacrum

src/runner/graph.rs

@@ -230,16 +230,24 @@ impl TasksGraph {
             self.mark_as_failed(child, ex, db, state, config, error, result, worker)?;
         }
 
-        match self.graph[node] {
+        // We need to mark_as_completed the node here (if it's a task),
+        // otherwise we'll later get stuck as the node is still considered
+        // running (but has actually failed).
+        let res = match self.graph[node] {
             Node::Task { ref task, .. } => {
                 log::debug!("marking task {:?} as failed", task);
-                task.mark_as_failed(ex, db, state, config, error, result)?
+                let res = task.mark_as_failed(ex, db, state, config, error, result);
+                if let Err(err) = &res {
+                    log::debug!("marking task {:?} as failed, failed: {:?}", task, err);
+                }
+                res
             }
             Node::CrateCompleted | Node::Root => return Ok(()),
-        }
+        };
 
         self.mark_as_completed(node);
-        Ok(())
+
+        res
     }
 
     pub(super) fn pending_crates_count(&self) -> usize {