pandoc markdown output drops attributes if href and text are identical

[jjallaire]

The following input results in the .clz being dropped:

echo "[https://example.com](https://example.com){.clz}" | pandoc --to markdown
<https://example.com>

Whereas if we change the text to diverge from the link then the attribute is preserved:

echo "[https://example.com/foo](https://example.com){.clz}" | pandoc --to markdown
[https://example.com/foo](https://example.com){.clz}

Observed in Pandoc 2.14.2 and 2.16.1 on Mac OX