no-branch on _draw_from_cache

hypothesis-python/src/hypothesis/internal/conjecture/datatree.py

@@ -798,7 +798,9 @@ def _draw_from_cache(self, ir_type, kwargs, *, key, random):
         # This number is chosen to balance memory/speed vs randomness. Ideally
         # we would sample uniformly from all not-yet-rejected children, but
         # computing and storing said children is not free.
-        if len(children) < 100:
+        # no-branch because coverage of the fall-through case here is a bit
+        # annoying.
+        if len(children) < 100:  # pragma: no branch
             for v in generator:
                 if v in rejected:
                     continue