Bugfix: correct time cmd duration in right prompt

Author: Serhii Nosov

fish_right_prompt.fish

@@ -61,5 +61,5 @@ function _is_multiplexed
 end
 
 function _convertsecs
- printf "%02d:%02d:%02d\n" (math $argv[1] / 3600) (math (math $argv[1] \% 3600) / 60) (math $argv[1] \% 60)
+  printf "%02d:%02d:%02d\n" (math -s0 $argv[1] / 3600) (math -s0 (math $argv[1] \% 3600) / 60) (math -s0 $argv[1] \% 60)
 end