[code][models] Ensure binary read is used when handling a CXX instance

It is done so currently as Databases are not Code contributions
since they have no owner.

beat/web/code/models.py

@@ -221,7 +221,10 @@ def set_source_code(instance, value):
 
 
 def get_source_code(instance):
-    return storage.get_file_content(instance, "source_code_file")
+    binary = False
+    if isinstance(instance, Code):
+        binary = instance.is_binary()
+    return storage.get_file_content(instance, "source_code_file", binary)
 
 
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