completion: use __gitcomp_builtin in _git_revert

The new completable option is --gpg-sign

In-progress options like --continue will be part of --git-completion-helper
then filtered out by _git_revert() unless the operation is in
progress. This helps keep marking of these operations in just one place.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -2692,19 +2692,19 @@ _git_reset ()
 	__git_complete_refs
 }
 
+__git_revert_inprogress_options="--continue --quit --abort"
+
 _git_revert ()
 {
 	__git_find_repo_path
 	if [ -f "$__git_repo_path"/REVERT_HEAD ]; then
-		__gitcomp "--continue --quit --abort"
+		__gitcomp "$__git_revert_inprogress_options"
 		return
 	fi
 	case "$cur" in
 	--*)
-		__gitcomp "
-			--edit --mainline --no-edit --no-commit --signoff
-			--strategy= --strategy-option=
-			"
+		__gitcomp_builtin revert "--no-edit" \
+			"$__git_revert_inprogress_options"
 		return
 		;;
 	esac