[PATCH 1 of 3] [py3] packaging: allow to run make with python3

[Yuya Nishihara]

On Thu, 04 Apr 2019 19:09:51 +0200, Philippe Pepiot wrote:
> # HG changeset patch
> # User Philippe Pepiot <philippe.pepiot at logilab.fr>
> # Date 1554397608 -7200
> #      Thu Apr 04 19:06:48 2019 +0200
> # Node ID c9030c811fdff71908344bb17f05bb71d314acc7
> # Parent  4ee906aa7b60fb6b113e4dc187fbb5a8f42e557c
> [py3] packaging: allow to run make with python3
> 
> Use "?=", otherwise the variable cannot be set from environment.
> 
> diff --git a/Makefile b/Makefile
> --- a/Makefile
> +++ b/Makefile
> @@ -5,7 +5,7 @@
>  # % make PREFIX=/opt/ install
>  
>  export PREFIX=/usr/local
> -PYTHON=python
> +PYTHON?=python

For the record, make variables can be explicitly overridden by command line
in 'make FOO=bar' form.