fetchart: update changelog

Author: wordofglass

docs/changelog.rst

@@ -40,9 +40,9 @@ Fixes:
 * Fix a crash when specifying non-ASCII format strings on the command line
   with the ``-f`` option to many commands. :bug:`2063`
 * :doc:`/plugins/fetchart`: Determine the file extension for downloaded images
-  based on the ``Content-Type`` header instead of hardcoding it to .jpg.
-  Reported in :bug:`2053`, which for now it does not fix due to
-  server-side issues, though.
+  based on the image's magic bytes and warn if result is not consistent with
+  the server-supplied ``Content-Type`` header instead of
+  hardcoding it to .jpg. :bug:`2053`
 
 1.3.18 (May 31, 2016)
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