Ampersands are not always escaped correctly in the Wiki Style Renderer.

Note that this problem is slightly hard to explain here, because this instance currently suffers this bug, but it may not suffer the bug in the future.
I will use "& a m p ;" to represent the ampersand escape sequence, but in reality I mean the sequence without spaces.

If I type an ampersand ('&') character in JIRA in a field with Wiki Style Renderer, then this is escaped out correctly in the HTML that is created, and the user will see "&".
However, if I type "& a m p ;", then no escaping is done and the user will only see "&", however they should see all four characters.

Note that the Default Style Renderer does actually work as expected.