Don't set http request headers with content None

jkseppan · jkseppan · commit 1133e83d72a9 · 2011-10-02T10:25:07.000+03:00
Attempts to fix issue #498. I can't reproduce the issue myself, so I don't know if this is the real culprit, but it shouldn't do any harm.
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -552,8 +552,13 @@ def https_request(self, req):
             url = req.get_full_url()
             if url in self.cache:
                 _, etag, lastmod = self.cache[url]
-                req.add_header("If-None-Match", etag)
-                req.add_header("If-Modified-Since", lastmod)
+                if etag is not None:
+                    req.add_header("If-None-Match", etag)
+                if lastmod is not None:
+                    req.add_header("If-Modified-Since", lastmod)
+            matplotlib.verbose.report(
+                "ViewVCCachedServer: request headers %s" % req.header_items(),
+                "debug")
             return req
 
         def https_error_304(self, req, fp, code, msg, hdrs):
