Makefile: Show error if target pep8 fails.

Makefile

@@ -1,7 +1,8 @@
 PEP8=pep8
 
 pep8:
-	find . -name "*.py" | xargs pep8
+	(find . -name "*.py" | xargs pep8 | perl -nle'\
+		print; $$a=1 if $$_}{exit($$a)')
 
 ghdocs:
 	contrib/doc2ghpages
@@ -14,3 +15,9 @@ bump:
 
 coverage:
 	(cd testproj; python manage.py test --figleaf)
+
+test:
+	(cd testproj; python manage.py test)
+
+releaseok: pep8 autodoc test
+