Don't log spam when all printers are busy

projects/tentacles/src/tentacles/workers.py

@@ -162,7 +162,8 @@ def assign_jobs(app: App, db: Db) -> None:
         if job.printer_id:
             continue
 
-        for printer in db.list_idle_printers():
+        idle = list(db.list_idle_printers())
+        for printer in idle:
             if (
                 job.analysis_id is not None
                 and printer.limit_x >= job.max_x
@@ -177,6 +178,7 @@ def assign_jobs(app: App, db: Db) -> None:
                 log.info(f"Mapped job {job.id} to printer {printer.id}")
                 break
         else:
+            if not idle:
                 log.info(f"Could not map job {job!r}")