makefile.python: partial revert off 9b48ae47, adds py2 support back

revert "makefile.python: ... drop build support py2" to get back Py2 support.
TPy2 support need virtualenv installed by the OS.

BTW: log environment and python version in travis's install phase

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

.travis.yml

@@ -11,6 +11,7 @@ addons:
   firefox: "latest"
 
 install:
+  - env; which python; python --version
   - make V=1 install
   - make V=1 gecko.driver
   - make V=1 node.env
@@ -29,6 +30,8 @@ stages:
 
 jobs:
   include:
+    - python: "2.7"
+      env: PY=2
     - python: "3.5"
     - python: "3.6"
     - stage: docker

utils/makefile.python

@@ -30,7 +30,7 @@ PYLINT_RC ?= .pylintrc
 TEST_FOLDER  ?= ./tests
 TEST         ?= .
 
-VTENV_OPTS   ?=
+VTENV_OPTS   = "--no-site-packages"
 PY_ENV       = ./local/py$(PY)
 PY_ENV_BIN   = $(PY_ENV)/bin
 PY_ENV_ACT   = . $(PY_ENV_BIN)/activate
@@ -41,6 +41,20 @@ ifeq ($(OS),Windows_NT)
   PY_ENV_ACT = $(PY_ENV_BIN)/activate
 endif
 
+ifeq ($(PYTHON),python)
+  VIRTUALENV   = virtualenv
+else
+  VIRTUALENV   = virtualenv --python=$(PYTHON)
+endif
+
+ifeq ($(KBUILD_VERBOSE),1)
+  PIP_VERBOSE =
+  VIRTUALENV_VERBOSE =
+else
+  PIP_VERBOSE = "-q"
+  VIRTUALENV_VERBOSE = "-q"
+endif
+
 python-help::
 	@echo  'makefile.python:'
 	@echo  '  pyenv | pyenv[un]install'
@@ -108,16 +122,13 @@ quiet_cmd_pyenvuninstall = PYENV     uninstall   $2
       cmd_pyenvuninstall = $(PY_ENV_BIN)/python -m pip $(PIP_VERBOSE) uninstall --yes $2
 
 # $2 path to folder where virtualenv take place
-# creating a virtualenv uses $(PYTHON) from the OS!
 quiet_cmd_virtualenv  = PYENV     usage: $ source ./$@/bin/activate
       cmd_virtualenv  = \
-	if [ ! -d "$(PY_ENV)" ];then                                    \
-		echo "PYENV     create virtualenv $2";                  \
-		$(PYTHON) -m venv $(VTENV_OPTS) $2;                     \
+	if [ ! -d "./$(PY_ENV)" ];then                                  \
+		$(VIRTUALENV) $(VIRTUALENV_VERBOSE) $(VTENV_OPTS) $2;   \
 	else                                                            \
 		echo "PYENV     using virtualenv from $2";              \
-        fi; \
-	echo "commands available at $(PY_ENV_BIN):"; ls $(PY_ENV_BIN) | $(FMT) ;
+        fi
 
 # $2 path to lint
 quiet_cmd_pylint      = LINT      $@