Many years ago I had a job offer at Badoo in the UK. After many rounds of going back-and-forth with the contract, me trying to better understand certain clauses, them going back to the lawyers, etc. I told them I'd be happy to sign if they removed the caluses that stated pretty much anything I created on or off hours belonged to them.
They went back to the lawyers and came back to me saying that this is not the first time this has been brought up, that the contract was standard across the org and was originally written for managerial types and C-suites, and that the company had never even considered taking over an employee's off-hours work, open source or otherwise.
I said good, then it should not be a problem to remove the clause. They said they would have another discussion and would really like it for me to join. I said great, then once you issue me a contract with that clause I'll be happy to join, assuming I hadn't found something else.
They never came back to me. For years I wondered if anything had actually changed. Reading this tweet I'm glad I declined.