Unlike the other attributes in a Commit object, the attributegpgsig is always set by theCommit constructor. If you look at all the previous lines, they are guarded with aif X is not None:.

Since the Commit object can then be created withgpgsig = None, this causes the__getattr__ in LazyMixin to not be called, which is responsible for calling_set_cache_ which ultimately calls_deserialize to populategpgsig.

This unfortunately causes the bug that ifgpgsig is thefirst attribute read, it returnsNone even when the commit is signed. For example, if before readinggpgsig, we read another attribute likemessage, readinggpgsig will work. This made the bug hard to discover and debug. 😞

I believe that this bug can be fixed just by adding aif gpgsig is not None: conditional in the line above.