These include:

MDL-14078: redirect() doubles the specified timeout when we haven't printed
           the page header and uses javascript to execute the redirect. This
           is interacting badly with some versions of IE and FF (at least
           3.0.x Windows version) that fireup javascript timers even if
           we already left the page where we set those up. Just print
           the page header (we are printing other content anyway) to
           make redirect respect our timeouts.

MDL-14071: All the relevant details are in the description of the bug :)

MDL-14297: This is probably the same as MDL-14078