Allow opt presets from internal libs. (#3819)

parlai/core/opt.py

@@ -161,15 +161,23 @@ def load_init(cls, optfile: str) -> Opt:
         elif PathManager.exists(user_filename):
             # use a user's custom opt preset
             return cls.load(user_filename)
-        elif pkg_resources.resource_exists("parlai", oa_filename):
-            # Maybe a bundled opt preset
-            return cls.load(pkg_resources.resource_filename("parlai", oa_filename))
         else:
-            raise FileNotFoundError(
-                f"Could not find filename '{optfile} or opt preset '{optfile}.opt'. "
-                "Please check https://parl.ai/docs/opt_presets.html for a list "
-                "of available opt presets."
-            )
+            # Maybe a bundled opt preset
+            for root in ['parlai', 'parlai_internal', 'parlai_fb']:
+                try:
+                    if pkg_resources.resource_exists(root, oa_filename):
+                        return cls.load(
+                            pkg_resources.resource_filename(root, oa_filename)
+                        )
+                except ModuleNotFoundError:
+                    continue
+
+        # made it through without a return path so raise the error
+        raise FileNotFoundError(
+            f"Could not find filename '{optfile} or opt preset '{optfile}.opt'. "
+            "Please check https://parl.ai/docs/opt_presets.html for a list "
+            "of available opt presets."
+        )
 
     def log(self, header="Opt"):
         from parlai.core.params import print_git_commit