twitter: fix preview bug that auto-linked @-mentions inside URLs

for snarfed/bridgy#527 (comment)

thanks again for reporting @jackysee!

README.md

@@ -294,6 +294,7 @@ Changelog
 ### 1.10 - unreleased
 * Twitter:
   * Update the publish character limit to 280. [Background.](https://twittercommunity.com/t/updating-the-character-limit-and-the-twitter-text-library/96425)
+  * Fix a [bug in `preview_create` that auto-linked @-mentions inside URLs](https://github.com/snarfed/bridgy/issues/527#issuecomment-346302800), e.g. Medium posts.
 
 ### 1.9 - 2017-10-24
 

granary/test/test_twitter.py

@@ -1779,6 +1779,18 @@ def test_ellipsize_real_tweet(self):
     actual_preview = self.twitter.preview_create(obj, include_link=source.INCLUDE_LINK).content
     self.assertEquals(preview, actual_preview)
 
+  def test_create_preview_dont_autolink_at_mentions_inside_urls(self):
+    """Don't autolink @-mentions inside urls.
+
+    https://github.com/snarfed/bridgy/issues/527#issuecomment-346302800
+    """
+    obj = copy.deepcopy(OBJECT)
+    del obj['image']
+    obj['content'] = u'時空黑洞都出現了，非常歡樂！LOL https://medium.com/@abc/xyz'
+    self.assertEquals(
+      u'時空黑洞都出現了，非常歡樂！LOL <a href="https://medium.com/@abc/xyz">medium.com/@abc/xyz</a>',
+      self.twitter.preview_create(obj).content)
+
   def test_tweet_article_has_different_format(self):
     """Articles are published with a slightly different format:
     "The Title: url", instead of "The Title (url)"

granary/twitter.py

@@ -99,7 +99,7 @@
 # username requirements and limits:
 # https://support.twitter.com/articles/101299#error
 # http://stackoverflow.com/a/13396934/186123
-MENTION_RE = re.compile(r'(^|[^@\w])@(\w{1,15})\b', re.UNICODE)
+MENTION_RE = re.compile(r'(^|[^\w@/\!?=&])@(\w{1,15})\b', re.UNICODE)
 
 # hashtag requirements and limits:
 # https://support.twitter.com/articles/370610