We use Markdown links in our MS Teams integration messages, for example we

display the summary line of a review request and make it link to the review

request page. Since the text for some links are user supplied, we want to

escape Markdown characters in the text so that they don't break the link.
Originally we had used Djblets' markdown_escape function to escape all

Markdown characters, but this turned out to look bad on the MS Teams mobile

app. The app has a bug where they don't properly display escaped Markdown

characters. The backslashes that are used for escaping are just plainly show.

Luckily, brackets are the only characters that are properly escaped in the

app, and these are really the only ones that would break the Markdown link.

So now we only escape the brackets.

Tested sending messages where the summary contained characters

  that would break the Markdown link. Saw the messages appear correctly

  with working links in the mobile and desktop apps.
Ran unit tests.