Ubuntu 16.04 can't compile latest changeset on default branch

[Marcin Kasperski]

> So the simple question is: can I compile it with python2.7 and if I can,
>
> how do I configure the Makefile or any other relevant to take 2.7. I
> can't find anything relevant in the Makefile.

In general, yes. Of course Mercurial supports 2.7.

Normal make uses PYTHON environment variable to let you decide.

In `make deb` case it looks like somebody switched default to py3.
Take a look at

   contrib/packaging/debian/rules 

(in mercurial sources). Those two lines are responsible:

   export HGPYTHON3=1
   export PYTHON=python3

Remove first of them, change second to 
   export PYTHON=python
and you should build fine.