In that example, I'm pretty sure that the 'require' line is compiled to opcodes, but not executed, until that line is reached. Supporting evidence: https://stackoverflow.com/questions/37880749/when-is-a-php-i...
So if there's a 10 second gap between the start of execution and the 'require' line being reached and evaluated, then any incompatible changes to the file being required within that 10 seconds will cause an error.
That actually makes sense because the codepath could be huge with huge surfaces of unused code.
With OpCache this could be solved so i guess lessin for me - deploy like this with opcache on.
Well, now you just have to manage cache invalidation. Piece of cake!
I kid, I kid, but seriously, now you have a different set of issues.