Docs Makefile needs to ensure git submodules are initialized

docs/Makefile

@@ -41,7 +41,7 @@ help:
 clean:
 	-rm -rf $(BUILDDIR)/*
 
-html:
+html: _themes
 	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
 	@echo
 	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
@@ -151,3 +151,7 @@ doctest:
 	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
 	@echo "Testing of doctests in the sources finished, look at the " \
 	      "results in $(BUILDDIR)/doctest/output.txt."
+
+_themes:
+	git clone git://github.com/Pylons/pylons_sphinx_theme.git _themes
+	cd ..; git submodule update --init; cd docs