> BTW, in a subsequent patch we could rename this to
> package-initialized, so the name reflects what the variable contains
> rather than what it's used for.

I don't think that's a good idea, since the most common usage of this
variable will be

    (setq package-initialized nil)

in the early init file, and that doesn't make much sense from a
readability perspective (are we asserting that package.el wasn't
initialized?).

> This is not used from C code, so make it a plain old defvar in
> startup.el.

Done. New patch attached.