bug#20373: automake 1.15 overwriting custom INSTALL file

[Emil]

Hi,

We have a custom INSTALL file in our project. Running `autoreconf -i`
(which AFAIK calls `automake --add-missing`) results in our INSTALL file
to be overwritten by the standard GNU INSTALL file, which is not what we
want.

BACKGROUND:
Here's a relevant part quoted from the automake manual
(https://www.gnu.org/software/automake/manual/html_node/Gnits.html):

> If the --add-missing option is given, automake will add a generic version
> of the INSTALL file as well as the COPYING file [...]. However, an
> existing COPYING file will never be overwritten by automake.

However it doesn't explicitly state whether an INSTALL file will be
overwritten or not, but I'm assuming it shouldn't be overwritten. Also,
while adding the `foreign` option to automake will prevent this behavior,
I wouldn't really consider it as a fix.

I also posted about this on the Unix & Linux SE:
http://unix.stackexchange.com/q/197238/103132

REPRODUCING:
You can find the minimal versions of our configure.ac, Makefile.am, and
autogen.sh scripts in the SE post, or as a gist here:
https://gist.github.com/emlai/1a42108bd787cadc3aa9

If needed, you can also take a look at the whole project branch which
reproduces the problem for me:
https://github.com/emlai/ivan/tree/automake-bug
You can simply download it and run the following commands to try if you
can reproduce the error:

        cd ivan-automake-bug
        head INSTALL
        ./autogen.sh
        head INSTALL

I'm using autoconf-2.69 and automake-1.15.

Cheers, Emil Laine <address@hidden>