Wait for GHA eval results instead of falling back to local evaluation

nixpkgs_review/review.py

@@ -4,6 +4,7 @@
 import subprocess
 import sys
 import tempfile
+import time
 from dataclasses import dataclass, field
 from enum import Enum
 from pathlib import Path
@@ -296,14 +297,23 @@ def build_pr(self, pr_number: int) -> dict[System, list[Attr]]:
         pr = self.github_client.pull_request(pr_number)
 
         packages_per_system: dict[System, set[str]] | None = None
-        if self.use_github_eval and all(system in PLATFORMS for system in self.systems):
-            # Attempt to fetch the GitHub actions evaluation result
-            print("-> Attempting to fetch eval results from GitHub actions")
-            packages_per_system = self.github_client.get_github_action_eval_result(pr)
-
-            if packages_per_system is not None:
-                print("-> Successfully fetched rebuilds: no local evaluation needed")
+        if self.use_github_eval:
+            assert all(system in PLATFORMS for system in self.systems)
+            print("-> Fetching eval results from GitHub actions")
 
+            packages_per_system = self.github_client.get_github_action_eval_result(pr)
+            if packages_per_system is None:
+                timeout: int = 10
+                print(f"...Results are not (yet) available. Retrying in {timeout}s")
+                while packages_per_system is None:
+                    sys.stdout.flush()
+                    print(".")
+                    time.sleep(timeout)
+                    packages_per_system = (
+                        self.github_client.get_github_action_eval_result(pr)
+                    )
+
+            print("-> Successfully fetched rebuilds: no local evaluation needed")
         else:
             packages_per_system = None