add some debugging for pre-rendered html

screenless/bureau/bureau.py

@@ -396,8 +396,16 @@ class Bureau(object):
                 print("fetched", url, "in", elapsed)
             return ret
 
-        weasyprint.HTML(url_fetcher=slowfetch,
-                        string=templ.render_unicode(**kwargs)).write_pdf(pdfpath)
+        html_rendered = weasyprint.HTML(url_fetcher=slowfetch,
+                        string=templ.render_unicode(**kwargs))
+
+        if self.log.getEffectiveLevel == logging.DEBUG:
+            with html_out as open("/tmp/debug.html", "w"):
+                html_out.write(html_rendered)
+                self.log.debug("debug html output at /tmp/debug.html")
+
+        html_rendered.write_pdf(pdfpath)
+        self.log.debug("wrote PDF to:", pdfpath)
         subprocess.call("lpr -o sides=two-sided-long-edge -o InputSlot=Upper "
                         + pdfpath, shell=True)