A link with an anchor text in a comment
This issue has been fixed. Read more on Meta Stack Overflow.
It seems that this change also affects the comments posted before.
Edit: Below is an older description of the issue, which no longer applies.
You can put a link in a comment by either writing a complete URL or using the
[…](http:…) syntax, just as in Markdown used for questions and answers. For example,
[TCS Stack Exchange](http://cstheory.stackexchange.com/) results in a link.
However, be careful when you use the latter syntax in a comment, because not all texts that would produce a link in Markdown also produce a link in comments. For example, if you enclose the text by a parenthesis like
([TCS Stack Exchange](http://cstheory.stackexchange.com/)) in a comment, the server does not recognize the syntax and turn only the URL part into a link.
The link syntax
[…](http:…) in comments is unreliable when a non-space character precedes or follows it. It is better not to use this syntax.
If you insist on using this syntax, an easy way to ensure that the server considers it as a hyperlink is to surround it by spaces. Some symbols such as a period and a comma seem to be allowed after the text.