Merge 4fe3039 into dd84176

lib/addressable/uri.rb

@@ -469,19 +469,13 @@ def self.unencode(uri, return_type=String, leave_encoded='')
           "Expected Class (String or Addressable::URI), " +
           "got #{return_type.inspect}"
       end
-      uri = uri.dup
-      # Seriously, only use UTF-8. I'm really not kidding!
-      uri.force_encoding("utf-8")
 
-      unless leave_encoded.empty?
-        leave_encoded = leave_encoded.dup.force_encoding("utf-8")
-      end
-
-      result = uri.gsub(/%[0-9a-f]{2}/iu) do |sequence|
+      result = uri.gsub(/%[0-9a-f]{2}/i) do |sequence|
         c = sequence[1..3].to_i(16).chr
-        c.force_encoding("utf-8")
+        c.force_encoding(sequence.encoding)
         leave_encoded.include?(c) ? sequence : c
       end
+
       result.force_encoding("utf-8")
       if return_type == String
         return result

spec/addressable/uri_spec.rb

@@ -5993,6 +5993,10 @@ def to_str
     expect(Addressable::URI.unencode_component("ski=%BA%DAɫ")).to eq("ski=\xBA\xDAɫ")
   end
 
+  it "should not fail with UTF-8 incompatible string (ISO-8859-1 encoding in this example)" do
+    expect(Addressable::URI.unencode_component("/M%E9thode/non/authoris\xE9e?param=\xFC".b)).to eq("/M\xE9thode/non/authoris\xE9e?param=\xFC")
+  end
+
   it "should result in correct percent encoded sequence as a URI" do
     expect(Addressable::URI.unencode(
       "/path?g%C3%BCnther", ::Addressable::URI