Rich Text Editor removes escape character (slash) in front of brackets

When people edit a page using the Rich Text Editor, confluence removes escape character (slash) in front of a minus sign in brackets like this:
(-)

See page history for the Confluence 2.10 release notes, where Sarah had to repeatedly restore the escape character after other people had edited the page using the Rich Text Editor.
http://confluence.atlassian.com/display/DOC/Confluence+2.10+Release+Notes
http://confluence.atlassian.com/pages/viewpreviousversions.action?pageId=168003443