add basic structrue logging to evaluator

ofborg/src/tasks/evaluate.rs

@@ -19,7 +19,7 @@ use std::time::Instant;
 use hubcaps::checks::CheckRunOptions;
 use hubcaps::gists::Gists;
 use hubcaps::issues::Issue;
-use tracing::{error, info, warn};
+use tracing::{debug_span, error, info, warn};
 
 pub struct EvaluationWorker<E> {
     cloner: checkout::CachedCloner,
@@ -249,6 +249,9 @@ impl<'a, E: stats::SysEvents + 'static> OneEval<'a, E> {
     // FIXME: remove with rust/cargo update
     #[allow(clippy::cognitive_complexity)]
     fn evaluate_job(&mut self) -> Result<worker::Actions, EvalWorkerError> {
+        let span = debug_span!("job", pr = ?self.job.pr.number);
+        let _enter = span.enter();
+
         let job = self.job;
         let repo = self
             .client_app