Don't count newlines as part of cmt prefix indent

Closes google#327

Author: bwendling

CHANGELOG

@@ -2,6 +2,12 @@
 # All notable changes to this project will be documented in this file.
 # This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.13.2] 2016-10-22
+### Fixed
+- REGRESSION: A comment may have a prefix with newlines in it. When calculating
+  the prefix indent, we cannot take the newlines into account. Otherwise, the
+  comment will be misplaced causing the code to fail.
+
 ## [0.13.1] 2016-10-17
 ### Fixed
 - Correct emitting a diff that was accidentally removed.

yapf/yapflib/comment_splicer.py

@@ -61,6 +61,8 @@ def _VisitNodeRec(node):
           # child in the next iteration...
           child_prefix = child.prefix.lstrip('\n')
           prefix_indent = child_prefix[:child_prefix.find('#')]
+          if '\n' in prefix_indent:
+            prefix_indent = prefix_indent[prefix_indent.find('\n') + 1:]
           child.prefix = ''
 
           if child.type == token.NEWLINE:

yapftests/reformatter_test.py

@@ -4056,6 +4056,23 @@ def _pack_results_for_constraint_or(cls, combination, constraints):
     reformatted_code = reformatter.Reformat(uwlines)
     self.assertCodeEqual(code, reformatted_code)
 
+  def testCommentWithNewlinesInPrefix(self):
+    code = textwrap.dedent("""\
+        def foo():
+            if 0:
+                return False
+                
+            #a deadly comment
+            elif 1:
+                return True
+
+
+        print(foo())
+        """)
+    uwlines = _ParseAndUnwrap(code)
+    reformatted_code = reformatter.Reformat(uwlines)
+    self.assertCodeEqual(code, reformatted_code)
+
 
 def _ParseAndUnwrap(code, dumptree=False):
   """Produces unwrapped lines from the given code.