Steps:

1. Paste the following code into an editor:

function foo() {
    /**
     */
    function bar() {
    }
}

(ugh, I don't know why GitHub is formatting this so badly... fix the code to be properly indented before continuing with the next steps)
2. Put the cursor after the **
3. Press enter, tab, type " * "
4. Now type @param {foo}

Result:
When you type the "{" the entire line gets back-indented one tab (back to zero indentation).
If you correct it and then finish typing, it gets back-indented again when you type the "}".

Expected:
No indentation change.

This repros in the vanilla CodeMirror demo too, so marking it as external.