Short-circuit if retry_delay_multiplicand_{min,max} are the same
Short-circuit if retry_delay_multiplicand_{min,max} are the same

Don't generate a random number if "retry_delay_multiplicand_min" and
"retry_delay_multiplicand_max" are the same value. As an added bonus
this also fixes an issue that was being see on Rubinius.

jzaleski/resque-retry,lantins/resque-retry,thenovices/resque-retry,thenovices/resque-retry,seomoz/resque-retry,thenovices/resque-retry,jzaleski/resque-retry,jzaleski/resque-retry,seomoz/resque-retry,seomoz/resque-retry,lantins/resque-retry,lantins/resque-retry