The mobile "Add discussion" button helpfully adds ~~~~ automatically to the end of your comment. Unfortunately, since editing a talk page section to reply to a thread doesn't do this, you still get into the habit of adding ~~~~ manually, which via force of habit leads to duplicate sigs whenever you use "Add discussion". I suggest either removing this automatic sig, or detecting "~~~~" at the end of the text and not adding it again if present.

Acceptance criteria

• Auto-add signature to replies. If "~~~~" is inside markup do not append.

QA steps

Use the beta cluster for this one.

• Make sure you are logged in and visit https://en.m.wikipedia.beta.wmflabs.org/wiki/Talk
• Click talk button at bottom of page
• Click add discussion in top right of overlay
• Write some text.
• click save in top right
• After the save has completed, in the talk overlay click your new discussion. Verify your username is inside the talk page section
• type in the reply box and hit save
• Verify your username is in the reply
• Run the above steps again but this time put "~~~~" (signature wikitext) somewhere inside your text. Ensure that your username doesn't appear twice.