Workaround for virtualenv and pip requirements.

Makefile

LIST_DEFAULT=sample_list.txt
OUT_DEFAULT=fixtures/amd.json
VENV_DIR=.venv
REQRUIREMENTS=requirements.txt

.PHONY: fetch venv requirements

fetch: venv requirements $(OUT_DEFAULT)
$(OUT_DEFAULT): $(LIST_DEFAULT)
    . $(VENV_DIR)/bin/activate; ./spider.py -i $(LIST_DEFAULT) -o $(OUT_DEFAULT)

venv: $(VENV_DIR)/bin/activate
$(VENV_DIR)/bin/activate:
    virtualenv --no-site-packages $(VENV_DIR)

requirements: venv $(VENV_DIR)/requirements.txt
$(VENV_DIR)/requirements.txt: $(REQRUIREMENTS)
    . $(VENV_DIR)/bin/activate; pip install -r $(REQRUIREMENTS)
    cp $(REQRUIREMENTS) $(VENV_DIR)/requirements.txt