[PATCH] completion: use __gitcomp_builtin for format-patch

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This helps format-patch gain completion for a couple new options,
notably --range-diff.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Of course it will be even better if I could complete the ref for
 --range-diff=, but maybe another day.

 contrib/completion/git-completion.bash | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index c8fdcf8644..065b922777 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1533,12 +1533,8 @@ _git_fetch ()
 }
 
 __git_format_patch_options="
-	--stdout --attach --no-attach --thread --thread= --no-thread
-	--numbered --start-number --numbered-files --keep-subject --signoff
-	--signature --no-signature --in-reply-to= --cc= --full-index --binary
-	--not --all --cover-letter --no-prefix --src-prefix= --dst-prefix=
-	--inline --suffix= --ignore-if-in-upstream --subject-prefix=
-	--output-directory --reroll-count --to= --quiet --notes
+	--full-index --not --all --no-prefix --src-prefix=
+	--dst-prefix= --notes
 "
 
 _git_format_patch ()
@@ -1551,7 +1547,7 @@ _git_format_patch ()
 		return
 		;;
 	--*)
-		__gitcomp "$__git_format_patch_options"
+		__gitcomp_builtin format-patch "$__git_format_patch_options"
 		return
 		;;
 	esac
-- 
2.19.1.647.g708186aaf9