bug#22308: intermittent problem generating autoloads

[Glenn Morris <rgm@gnu.org>]

Eli Zaretskii wrote:

> When that happens, do you see binary null bytes in the autoloads file?

As I've said before, I have no special access to hydra.
The output of failed builds is not kept, so we don't have that file.

I have seen similar issues twice in my own daily builds (in mid-Dec), so
the issue is not specific to hydra.

> This stopped happening for me since the undo issues were fixed on the
> emacs-25 branch.  I thought that was what fixed these.

Maybe yours was a different issue (I'm surprised undo has any relevance
to autoload generation).

> I cannot debug this unless it happens again.

It's a Heisenbug. If it happens again on hydra you'll get no more
information than you have now.

Suggestions:

make autoloads many times (using bootstrap-emacs may be relevant) in a
loop till it happens again

insert anticipatory debug code into autoload.el