Why does getSavedCall() never return null and sometimes even work without having called saveCall beforehand

[Nasicus]

See this issue: #3061

And the resulting question:

Ok turns out I'm just stupid I forgot to call saveCall(call); before calling startActivityForResult(call, <intent>, RC_AUTH);

What still surprises me though is:

• Why does it work sometimes?
• Why does getSavedCall() always return an instance? I debugged a lot and it was NEVER null.

Would nice if someone could enlighten me here ? :)