Don't output html to a tempdir, but keep them.

docs/check_sphinx.py

@@ -10,7 +10,7 @@ def test_linkcheck(tmpdir):
 
 def test_build_docs(tmpdir):
     doctrees = tmpdir.join("doctrees")
-    htmldir = tmpdir.join("html")
+    htmldir = "html" #we want to keep the docs
     subprocess.check_call([
         "sphinx-build", "-W", "-bhtml",
           "-d", str(doctrees), ".", str(htmldir)])