Links to other issues are broken (BB-6713)

Links to other issues are broken in a few ways:

1. Links added by 'issue' link are wrong. For example, when adding the link to issue 401 from issue 402, the link is stored as .../402/401 and links to current issue instead. Minor issue is that default link name is URL, so it looks like [https://bitbucket.org... issue|issue]. Maybe the arguments got swapped?
2. Duplicate does not have link, instead, ugly <<issue 452>> is shown.
3. #<number> is still converted to issue, but without a link and with ugly <<issue 452> formatting.

I feel like all these errors have common cause.