*
 *  2. If there is a connection in the pool that can satisfy the request it is used. Note that it is
 *     possible for shared exchanges to make requests to different host names! See
 *     [RealConnection.isEligible] for details.
 *
 *  3. Attempt plans from prior connect attempts for this call. These occur as either follow-ups to
 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost