Fix hang in unsatisfyable range or HEAD request for static file

Also update CHANGES with last three changes.

Author: rouilj

CHANGES.txt

@@ -78,6 +78,12 @@ Fixed:
 - issue2551196 - Unset labelprop of a Multilink can lead to Python
   error when using context/history. (reported and initial patch: Nagy
   Gabor, John Rouillard)
+- Fix roundup-server to pass If-Range http header so Ranges work
+  better. (John Rouillard)
+- issue2551183 - Replace references to distutils in
+  roundup/dist/command (John Rouillard)
+- Fix hang if Range request was not able to be satified or a HEAD
+  request was done.
 
 Features:
 

roundup/cgi/client.py

@@ -2524,6 +2524,8 @@ def write_file(self, filename):
         # indicating an invalid range.
         if (self.env['REQUEST_METHOD'] == 'HEAD'
             or self.response_code == http_.client.REQUESTED_RANGE_NOT_SATISFIABLE):
+            self.setHeader("Content-Length", 0)
+            self.header()
             return
         # Use the optimized "sendfile" operation, if possible.
         if hasattr(self.request, "sendfile"):