Don't mention issues in code blocks or links

It often happens that stack traces, etc include numbers formatted as #xxx. If those are put into gitlab it shouldn't generate a mention in that issue:

Test #1

Looking at #1 (closed) right now I noticed it also happens in URLs (look at the previous mentions). They should also be excluded.

This is more interesting given that it knows not to linkify them in the original issue...

Should be fixed in GitLab 7.0. Reort back if the error still exists

Status changed to closed

mentioned in commit fc63690d

mentioned in merge request !14785