Merge pull request #808 from tricknotes/fix-sprockets-base-unescape-for-3.x

Fix `Sprockets::Base#unescape` to avoid unexpected change landed in 3.7.4

Author: byroot

lib/sprockets/legacy.rb

@@ -155,7 +155,7 @@ def matches_filter(filters, logical_path, filename)
       end
 
       def unescape(str)
-        URIUtils::URI_PARSER.unescape(str)
+        str = URIUtils::URI_PARSER.unescape(str)
         str.force_encoding(Encoding.default_internal) if Encoding.default_internal
         str
       end