Fix No blank line after if/for/while/def

yapf/__init__.py

@@ -108,6 +108,8 @@ def main(argv):
 
     source = [line.rstrip() for line in original_source]
     source[0] = _removeBOM(source[0])
+    # filter all the tuples with empty space
+    source = list(filter(None, source))
 
     try:
       reformatted_source, _ = yapf_api.FormatCode(

yapftests/main_test.py

@@ -137,3 +137,11 @@ def testHelp(self):
       self.assertIn('indent_width=4', help_message)
       self.assertIn('The number of spaces required before a trailing comment.',
                     help_message)
+  def testExtraBlankLine(self):
+    code = 'if True:\n\n\n\n\t print(2)'
+    yapf_code = 'if True:\n  print(2)\n'
+    with patched_input(code):
+      with captured_output() as (out, _):
+        ret = yapf.main([])
+        self.assertEqual(ret, 0)
+        self.assertEqual(out.getvalue(), yapf_code)