Add test for buggy ruby method newline

Currently, inserting a newline after a ruby method will incorrectly
cause the following line to repeat the method header. This commit
adds a test case to illustrate the bug.

test/indent/ruby/method-definition-shouldnt-duplicate/cmd

@@ -0,0 +1 @@
+c<ret><esc>

test/indent/ruby/method-definition-shouldnt-duplicate/in

@@ -0,0 +1,3 @@
+class Test
+    def test%( )
+end

test/indent/ruby/method-definition-shouldnt-duplicate/out

@@ -0,0 +1,5 @@
+class Test
+    def test
+        
+    end
+end

test/indent/ruby/method-definition-shouldnt-duplicate/rc

@@ -0,0 +1,3 @@
+source "%val{runtime}/colors/default.kak"
+source "%val{runtime}/rc/base/ruby.kak"
+set buffer filetype ruby