Get rid of wc dependency when showing ahead/behind info

functions/vcs.zsh

@@ -33,12 +33,12 @@ function +vi-git-aheadbehind() {
 
     # for git prior to 1.7
     # ahead=$(command git rev-list origin/${branch_name}..HEAD | wc -l)
-    ahead=$(command git rev-list "${branch_name}"@{upstream}..HEAD 2>/dev/null | wc -l)
+    ahead=$(command git rev-list --count "${branch_name}"@{upstream}..HEAD 2>/dev/null)
     (( ahead )) && gitstatus+=( " $(print_icon 'VCS_OUTGOING_CHANGES_ICON')${ahead// /}" )
 
     # for git prior to 1.7
     # behind=$(command git rev-list HEAD..origin/${branch_name} | wc -l)
-    behind=$(command git rev-list HEAD.."${branch_name}"@{upstream} 2>/dev/null | wc -l)
+    behind=$(command git rev-list --count HEAD.."${branch_name}"@{upstream} 2>/dev/null)
     (( behind )) && gitstatus+=( " $(print_icon 'VCS_INCOMING_CHANGES_ICON')${behind// /}" )
 
     hook_com[misc]+=${(j::)gitstatus}