bug#17629: Can't build emacs-24 branch

[Glenn Morris <rgm@gnu.org>]

Eli Zaretskii wrote:

>> In a fresh checkout and with a clean tree:
>
> This doesn't seem to be a clean tree:
[...]
> Did you switch to the emacs-24 branch in the same git repository, and
> then typed the command above?  If so, either "make bootstrap" or clone
> a separate repository, switch to emacs-24 there, and then your
> commands should work.
>
> In Emacs development, the trunk and the release branch diverge very
> quickly, so "make clean" is not enough to give you a "clean tree".


The main point is that `make clean' does not delete the compiled lisp
files (and cannot, since they are prebuilt in lisp tarfiles).
`make maintainer-clean', or `make bootstrap' does.
Always use `make bootstrap' if CPU time is not a factor, even when
building the same branch.

(Presumably this issue is going to occur more in the git-era, since it
doesn't have shared repos.)