True.
And while I expected "some" issues from the major changes I made underneath, completely forgetting about one of the code files even existing created half of them. Python for all its positives is a caveman's language in terms of lack of proper refactoring tools and code analysis. Which makes development a case of "code & fix", which I hate. And if as I have been you jump in and out in spare moments at work or while watching TV at home, it is easy to forget/miss something. Then without any type or compile checking the only way of catching it is to test every of code. Without any unit testing support like I would have in .NET... sigh...
Look at the whats new with every calibre releases and there are frequently regression fixes, even an uber experienced full-time Python guru like Kovid gets tripped up - so that doesn't leave much chance for the rest of us without even more time/effort.
We are definitely close on this release though...