Handle deleted fuzz targets in split builds (#4410)

Fixes: https://buganizer.corp.google.com/issues/377701732

Author: jonathanmetzman

src/clusterfuzz/_internal/build_management/build_manager.py

@@ -1156,7 +1156,13 @@ def _setup_split_targets_build(bucket_path, fuzz_target, revision=None):
   bucket_path = environment.get_value('FUZZ_TARGET_BUILD_BUCKET_PATH')
   if not fuzz_target:
     raise BuildManagerError(
-        'Failed to choose a fuzz target (path=%s).' % bucket_path)
+        f'Failed to choose a fuzz target (path={bucket_path}).')
+
+  # Check this so that we handle deleted targets properly.
+  targets_list = _get_targets_list(bucket_path)
+  if fuzz_target not in targets_list:
+    raise errors.BuildNotFoundError(revision, environment.get_value('JOB_NAME'))
+
   fuzz_target_bucket_path = _full_fuzz_target_path(bucket_path, fuzz_target)
   if not revision:
     revision = _get_latest_revision([fuzz_target_bucket_path])

src/clusterfuzz/_internal/tests/core/build_management/build_manager_test.py

@@ -1741,6 +1741,9 @@ def test_target_no_longer_built(self):
       build_manager._pick_random_fuzz_target_for_split_build(
           target_weights={'target4': 1})
 
+    with self.assertRaises(errors.BuildNotFoundError):
+      build_manager.setup_build(fuzz_target='target4')
+
 
 class GetPrimaryBucketPathTest(unittest.TestCase):
   """Tests for get_primary_bucket_path."""