bug#12135: 24.1.50; compatibility between compiled files in emacs-24.1 and 24.2

[Stefan Monnier]

>> Yes, and these files should work correctly under Emacs-24.2 (at least
>> I did try to preserve this compatibility).
> No, they don't either, try it.

Indeed, I see that C-x c M-x doesn't work when compiled with Emacs-24.1
and run with the trunk.
But since we don't get any error message, I'm not sure where to start
looking for the cause.  You pointed the finger at flet, so maybe you
have some idea (or gut feeling)?

I did see that compiling all files with Emacs-24.1 (or Emacs-23) and
then recompiling helm-command.el with Emacs trunk makes the C-x c M-x
test case work again under trunk, so the problem seems to be somewhere
in helm-command.elc.

Maybe there an error is signalled but is then silenced by one of the
many ignore-errors?  If so, would you have some idea as to which
ignore-errors could be turned into with-demoted-errors to try and make
an error message appear?


        Stefan