Bug #212: variable %i always 0.0.0.0

Bug #212: variable %i always 0.0.0.0

This patch extends errorCon() with a request_t argument, pulling some of the common
details of the request:

  ->request
  ->src_addr

Also cleaned all the duplicated related code.

Some of the 2.6 failing cases was already fixed in 3.0 using
clientBuildError(), but there are many other failing cases now fixed by this
patch.