travis: On Python3 use python3-version of pep8 #38

Previously pep8 and pyflakes were installed using the default system Python.
This changes 'make travis' to use the current Python version for those scripts as well.
This affects pep8, at least: on Python3 it complains about space in `print (...)`.

.travis.yml

 language: python
-env:
- - PYTHONVER=2.6
- - PYTHONVER=2.7
- - PYTHONVER=3.3
+python:
+ - "2.6"
+ - "2.7"
+ - "3.3"
 matrix:
   allow_failures:
-    - env: PYTHONVER=3.3
-script: sudo -E make travis
+    - python: "3.3"
+script: make travis
 notifications:
   email: false

Makefile

 # This file is renamed to "Makefile.ext" in release tarballs so that setup.py won't try to
 # run it.  If you want setup.py to run "make" automatically, rename it back to "Makefile".
 
-PYTHON ?= python${PYTHONVER}
+PYTHON ?= python${TRAVIS_PYTHON_VERSION}
 CYTHON ?= cython
 
 all: gevent/gevent.core.c gevent/gevent.ares.c gevent/gevent._semaphore.c gevent/gevent._util.c
@@ -37,10 +37,10 @@ whitespace:
 	! find . -not -path "./.git/*" -not -path "./build/*" -not -path "./libev/*" -not -path "./c-ares/*" -not -path "./doc/_build/*" -type f | xargs egrep -l " $$"
 
 pep8:
-	pep8 .
+	${PYTHON} `which pep8` .
 
 pyflakes:
-	util/pyflakes.py
+	${PYTHON} util/pyflakes.py
 
 lint: whitespace pep8 pyflakes
 
@@ -62,10 +62,10 @@ travis:
 	make whitespace
 
 	pip install -q pep8
-	make pep8
+	PYTHON=python make pep8
 
 	pip install -q pyflakes
-	make pyflakes
+	PYTHON=python make pyflakes
 
 	sudo add-apt-repository -y ppa:chris-lea/cython
 	sudo apt-get -qq -y update
@@ -77,11 +77,11 @@ travis:
 
 	ack -w subprocess greentest/ -l -v | python -c 'import sys; print "\n".join(line.split("/")[-1].strip() for line in sys.stdin)' > greentest/tests_that_dont_use_subprocess.txt
 
-	make travistest
+	sudo -E make travistest
 
-	apt-get install ${PYTHON}-dbg
+	sudo -E apt-get install ${PYTHON}-dbg
 
-	PYTHON=${PYTHON}-dbg GEVENTSETUP_EV_VERIFY=3 make travistest
+	sudo -E PYTHON=${PYTHON}-dbg GEVENTSETUP_EV_VERIFY=3 make travistest
 
 
 .PHONY: clean all doc pep8 whitespace pyflakes lint travistest travis