bug#23692: 25.1.50; Package.el gets confused if file has no autoloads (could be a bug in update-directory-autoloads)

[Glenn Morris]

Stefan Monnier wrote:

> -      (when changed
> +      (if (not changed)
> +          (set-buffer-modified-p nil)

I guess that will work. Some vague thoughts:

i) I guess now autoload will sometimes not create any output file.
Does that matter?

ii) I wonder what this means for reproducibility of the loaddefs file.
IIRC When building Emacs itself, the loaddefs file can change if you:
make -j8 bootstrap; make -C lisp autoloads
due to changes in "files with no autoloads" section owing to generated
files being created in parallel with loaddefs.el (this is really a
failure in dependency tracking for loaddefs, but it's harmless).
But it does finally converge to a fixed state. Will it still do so if
the loaddefs file sometimes isn't written?

iii) Would applying a move-if-change style logic be better?