Automate updating git-completion.bash a bit

index cfd24c5764..0cfa489a8e 100644
@@ -36,6 +36,10 @@
 #
 #     When set to "1", do not include "DWIM" suggestions in git-checkout
 #     completion (e.g., completing "foo" when "origin/foo" exists).
+#
+#   GIT_COMPLETION_OPTIONS
+#
+#     When set to "all", complete all possible options
 
 case "$COMP_WORDBREAKS" in
 *:*) : great ;;

@@ -284,24 +288,33 @@ __gitcomp ()
 #
 #    __gitcomp "$(git xxx --git-completion-helper) ..."
 #
-# except that the value from $(git) is cached
+# except that the output is cached. Accept 1-3 arguments:
+# 1: the git command to execute, this is also the cache key
+# 2: extra options to be added on top (e.g. negative forms)
+# 3: options to be excluded
 __gitcomp_builtin ()
 {
 	# spaces must be replaced with underscore for multi-word
 	# commands, e.g. "git remote add" becomes remote_add.
 	local cmd="$1"
-	shift
+	local incl="$2"
+	local excl="$3"
 
 	local var=__gitcomp_builtin_"${cmd/-/_}"
 	local options
 	eval "options=\$$var"
 
 	if [ -z "$options" ]; then
-		declare -g "$var=$(__git ${cmd/_/ } --git-completion-helper)"
-		eval "options=\$$var"
+		# leading and trailing spaces are significant to make
+		# option removal work correctly.
+		options=" $(__git ${cmd/_/ } --git-completion-helper=$GIT_COMPLETION_OPTIONS) $incl "
+		for i in $excl; do
+			options="${options/ $i / }"
+		done
+		eval "$var=\"$options\""
 	fi
 
-	__gitcomp "$options $*"
+	__gitcomp "$options"
 }
 
 # Variation of __gitcomp_nl () that appends to the existing list of

@@ -1096,12 +1109,13 @@ __git_count_arguments ()
 }
 
 __git_whitespacelist="nowarn warn error error-all fix"
+__git_am_inprogress_options="--skip --continue --resolved --abort"
 
 _git_am ()
 {
 	__git_find_repo_path
 	if [ -d "$__git_repo_path"/rebase-apply ]; then
-		__gitcomp "--skip --continue --resolved --abort"
+		__gitcomp "$__git_am_inprogress_options"
 		return
 	fi
 	case "$cur" in

@@ -1110,7 +1124,8 @@ _git_am ()
 		return
 		;;
 	--*)
-		__gitcomp_builtin am "--no-utf8"
+		__gitcomp_builtin am "--no-utf8" \
+			"$__git_am_inprogress_options"
 		return
 	esac
 }

@@ -1272,16 +1287,19 @@ _git_cherry ()
 	__git_complete_refs
 }
 
+__git_cherry_pick_inprogress_options="--continue --quit --abort"
+
 _git_cherry_pick ()
 {
 	__git_find_repo_path
 	if [ -f "$__git_repo_path"/CHERRY_PICK_HEAD ]; then
-		__gitcomp "--continue --quit --abort"
+		__gitcomp "$__git_cherry_pick_inprogress_options"
 		return
 	fi
 	case "$cur" in
 	--*)
-		__gitcomp_builtin cherry-pick
+		__gitcomp_builtin cherry-pick "" \
+			"$__git_cherry_pick_inprogress_options"
 		;;
 	*)
 		__git_complete_refs

@@ -2674,16 +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 "$cur" in
 	--*)
-		__gitcomp_builtin revert "--no-edit"
+		__gitcomp_builtin revert "--no-edit" \
+			"$__git_revert_inprogress_options"
 		return
 		;;
 	esac