Empty Project Builder data created at some point before most recent commit does not save when modified

[svetogam]

One project I had with an empty local config file from before the newest changes wouldn't save new routines when I added them. I deleted the local config file and opened the project again, and then it started to save normally.

I think e6bbd37 is the culprit.

This is just a one-time upgrade inconvenience. Saying somewhere to delete empty local config files created before the newest version would fix it.