remote http: use Content-MD5 header if there is not ETag available

Fix #1412

tests/utils/httpd.py

@@ -17,12 +17,26 @@ class ETagHandler(SimpleHTTPRequestHandler):
         SimpleHTTPRequestHandler.end_headers(self)
 
 
+class ContentMD5Handler(SimpleHTTPRequestHandler):
+    def end_headers(self):
+        file = self.translate_path(self.path)
+
+        if not os.path.isdir(file) and os.path.exists(file):
+            with open(file, 'r') as fd:
+                md5 = hashlib.md5(fd.read().encode('utf8')).hexdigest()
+                self.send_header('Content-MD5', md5)
+
+        SimpleHTTPRequestHandler.end_headers(self)
+
+
 class StaticFileServer:
     __server_lock = threading.Lock()
 
-    def __init__(self):
+    def __init__(self, handler='etag'):
+        handler_class = ETagHandler if handler == 'etag' else ContentMD5Handler
+
         self.__server_lock.acquire()
-        self.httpd = HTTPServer(('localhost', 8000), ETagHandler)
+        self.httpd = HTTPServer(('localhost', 8000), handler_class)
 
     def __enter__(self):
         self.server_thread = threading.Thread(target=self.httpd.serve_forever)