Just found out it was showing the content of readme.html I have in the repository root which seems to be a feature. But why does it pick up readme.html when it cannot render it as HTML (it showed it as plain text including html tags and everything) - it is better to ignore in that case.
I worked around the issue by adding another readme - this time with readme.md extension that is now correctly showing up on the overview page instead of readme.html.
Not displaying it is fine. What I am questioning is, why does it even appear on the Overview page, when it has html extension (i.e. if I have readme.html in the root of my repo, it is going to show up in the Overview page, but looks like a crap, as it is shown as plain text - so what's the point of showing it??)
Let me describe my experience:
1) made a few commits to my repo (one of the changes were, that I added readme.html into the root - this was *not* intended for the overview tab - I wasn't even aware of that feature)
2) suddenly noticed the Overview page looks like crap - I thought there is a bug somewhere in bitbucket which causes it to show some random stuff from the repo on the Overview page
3) then I though, maybe there is a feature that shows the content of a readme file - did a search on that and found there is such feature - anyway, it does not support HTML, so why is it picking my readme.html file??
4) added readme.md with some simple content to make sure bitbucked does not pick readme.html
Looks like a bug to me. It should not be picking up readme with extensions it does not support.