Before this, we only ever ran against system python preinstalled on
travis (i.e. 2.7 and 3.2). This change makes sure that Vim is always
build and run against the correct python version in the virtual env.
Also adds mercurial (HEAD) Vim as a testing target.
This patch took me forever to get right. At least 2 months and ~200
travis runs of trial and error - there is just too much finicky going on
with the many virtual envs on travis, Vims strange build system that
does not use python-config and LD_LIBRARY_PATH loading. En plus, the
debugging insights one can glance from travis runs are rather limited.
Detailed changes:
- Uses less sudo and only outside of scripts.
- Build correct version of Vim against correct version of Python. This
needs some LD_LIBRARY_PATH magic to make sure that Vim finds the
correct Python libraries at runtime.
- Removes dirty hack that overwrote /usr/bin/vim with the correct Vim
version to run. The test_all.py script now takes the Vim binary as a
parameter.
