Remove content-language in pre compressed brotli (#248)

Author: nlemoine

h5bp/web_performance/pre-compressed_content_brotli.conf

@@ -12,6 +12,8 @@
 # brotli-compressed resources.
 # https://www.chromestatus.com/feature/5420797577396224
 #
+# (1) See https://httpd.apache.org/docs/2.4/en/mod/mod_mime.html#multipleext
+#
 # https://httpd.apache.org/docs/current/mod/mod_brotli.html#precompressed
 
 <IfModule mod_headers.c>
@@ -44,6 +46,9 @@
         # Force proxies to cache brotlied and non-brotlied files separately
         Header append Vary Accept-Encoding
 
+        # (1) Remove content-language header added by mod_mime
+        RemoveLanguage .br
+
     </FilesMatch>
 
     # Serve correct encoding type