[Fix #1449] Detect unrecognized style in MultilineOperationIndentation

It's when we forget to call unrecognized_style_detected that we
can get the strange Enabled: true setting in a .rubocop_todo.yml
file.

CHANGELOG.md

@@ -7,6 +7,7 @@
 * [#801](https://github.com/bbatsov/rubocop/issues/801): New style `context_dependent` for `Style/BracesAroundHashParameters` looks at preceding parameter to determine if braces should be used for final parameter. ([@jonas054][])
 * [#1441](https://github.com/bbatsov/rubocop/issues/1441): Correct the logic used by `Style/Blocks` and other cops to determine if an auto-correction would alter the meaning of the code. ([@jonas054][])
 * [#1427](https://github.com/bbatsov/rubocop/issues/1427): Excluding directories on the top level is now done earlier, so that these file trees are not searched, thus saving time when inspecting projects with many excluded files. ([@jonas054][])
+* [#1449](https://github.com/bbatsov/rubocop/issues/1449): Handle the case in `MultilineOperationIndentation` where instances of both correct style and unrecognized (plain wrong) style are detected during an `--auto-gen-config` run. ([@jonas054][])
 
 ### Bugs fixed
 

lib/rubocop/cop/style/multiline_operation_indentation.rb

@@ -51,7 +51,9 @@ def check(range, node, lhs, rhs)
 
         def incorrect_style_detected(range, node, lhs, rhs)
           add_offense(range, range, message(node, lhs, rhs)) do
-            unless offending_range(node, lhs, rhs, alternative_style)
+            if offending_range(node, lhs, rhs, alternative_style)
+              unrecognized_style_detected
+            else
               opposite_style_detected
             end
           end

spec/rubocop/cop/style/multiline_operation_indentation_spec.rb

@@ -198,7 +198,7 @@
                                   '`unless` statement spanning multiple ' \
                                   'lines.'])
       expect(cop.highlights).to eq(['.b'])
-      expect(cop.config_to_allow_offenses).to be_nil
+      expect(cop.config_to_allow_offenses).to eq('Enabled' => false)
     end
 
     it 'registers an offense for misaligned operands in while condition' do
@@ -399,6 +399,18 @@
       expect(cop.messages).to be_empty
     end
 
+    it 'registers an offense for correct + unrecognized style' do
+      inspect_source(cop,
+                     ['a ||',
+                      '  b',
+                      'c and',
+                      '    d'])
+      expect(cop.messages).to eq(['Use 2 (not 4) spaces for indenting an ' \
+                                  'expression spanning multiple lines.'])
+      expect(cop.highlights).to eq(%w(d))
+      expect(cop.config_to_allow_offenses).to eq('Enabled' => false)
+    end
+
     it 'registers an offense for aligned operatiors in assignment' do
       inspect_source(cop,
                      ['formatted_int = int_part',