Fix detecting strings with hashtag as requiring quotes

tests/rules/test_quoted_strings.py

@@ -330,7 +330,8 @@ class QuotedTestCase(RuleTestCase):
                    '- "%wheel ALL=(ALL) NOPASSWD: ALL"\n'
                    '- \'"quoted"\'\n'
                    '- "\'foo\' == \'bar\'"\n'
-                   '- "\'Mac\' in ansible_facts.product_name"\n',
+                   '- "\'Mac\' in ansible_facts.product_name"\n'
+                   '- \'foo # bar\'\n',
                    conf)
         self.check('---\n'
                    'k1: ""\n'

yamllint/rules/quoted_strings.py

@@ -160,7 +160,7 @@ def _quotes_are_needed(string):
     try:
         a, b = loader.get_token(), loader.get_token()
         if (isinstance(a, yaml.ScalarToken) and a.style is None and
-                isinstance(b, yaml.BlockEndToken)):
+                isinstance(b, yaml.BlockEndToken) and a.value == string):
             return False
         return True
     except yaml.scanner.ScannerError: