**Steps to reproduce:**

In user preference, turn on `Export mathemaical formulas as MathJax`

Type `\multline*`

to create a multline environment

In the menu, click

`Edit » Copy to html`

The result is

```
<center>
\(\displaystyle \begin{array}{l}
\sum_{k = 0}^{\infty} (\alpha + k)
(\alpha + k - 1) a_k x^{\alpha + k} -
\sum_{k = 0}^{\infty} (\alpha + k)
(\alpha + k - 1) a_k x^{\alpha + k - 1}\\
+ \sum_{k = 0}^{\infty} 3
(\alpha + k) a_k x^{\alpha + k} + \sum_{k =
0}^{\infty} a_k x^{\alpha + k}
= 0
\end{array}\)
</center>
```

`multline`

environment becomes `array`

environment, so the second line is left-aligned (but should be right-aligned).