Link conversion might have context sensitive bug

[lachsalter]

To explain the problem I stumbled upon is that if I convert a text with a link with markdown it does not create the correct html when the text contains a lone ':' , but works when there is ':' but also works when the ':' is preceeded by 'Text' for example. To show what I mean here is an example, the following lines:

say markdown('Test: [https://koya.gg/commands](https://koya.gg/commands)');
say markdown('Test\: [https://koya.gg/commands](https://koya.gg/commands)');
say markdown('**Test**: [https://koya.gg/commands](https://koya.gg/commands)');

Return:

Test: [https://koya.gg/commands](https://koya.gg/commands)<br />
<p>Test\: <a href="https://koya.gg/commands">https://koya.gg/commands</a></p>
<p><strong>Test</strong>: <a href="https://koya.gg/commands">https://koya.gg/commands</a></p>

The return from the second and third line are expected, the return from the first line however seems buggy to me. I would have expected:

<p>Test: <a href="https://koya.gg/commands">https://koya.gg/commands</a></p>

Best regards and thank you for your time.