Documentation/lint-manpages: bubble up errors

The "lint-manpages.sh" script does not return an error in case any of
its checks fail. While this is faithful to the implementation that we
had as part of the "check-docs" target before the preceding commit, it
makes it hard to spot any violations of the rules via the corresponding
CI job, which will of course exit successfully, too.

Adapt the script to bubble up errors.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/lint-manpages.sh

@@ -12,7 +12,9 @@ EOF
 	sed -n -e 's/.*XXX \(.*\) YYY.*/\1/p'
 }
 
-check_missing_docs () {
+check_missing_docs () (
+	ret=0
+
 	for v in $ALL_COMMANDS
 	do
 		case "$v" in
@@ -32,6 +34,7 @@ check_missing_docs () {
 		if ! test -f "$v.txt"
 		then
 			echo "no doc: $v"
+			ret=1
 		fi
 
 		if ! sed -e '1,/^### command list/d' -e '/^#/d' ../command-list.txt |
@@ -41,11 +44,15 @@ check_missing_docs () {
 			git)
 				;;
 			*)
-				echo "no link: $v";;
+				echo "no link: $v"
+				ret=1
+				;;
 			esac
 		fi
 	done
-}
+
+	exit $ret
+)
 
 check_extraneous_docs () {
 	(
@@ -61,15 +68,19 @@ check_extraneous_docs () {
 		    -e 's/\.txt//'
 	) | (
 		all_commands="$(printf "%s " "$ALL_COMMANDS" "$BUILT_INS" "$EXCLUDED_PROGRAMS" | tr '\n' ' ')"
+		ret=0
 
 		while read how cmd
 		do
 			case " $all_commands " in
 			*" $cmd "*) ;;
 			*)
-				echo "removed but $how: $cmd";;
+				echo "removed but $how: $cmd"
+				ret=1;;
 			esac
 		done
+
+		exit $ret
 	)
 }
 
@@ -77,7 +88,21 @@ BUILT_INS="$(extract_variable BUILT_INS)"
 ALL_COMMANDS="$(extract_variable ALL_COMMANDS)"
 EXCLUDED_PROGRAMS="$(extract_variable EXCLUDED_PROGRAMS)"
 
-{
-	check_missing_docs
-	check_extraneous_docs
-} | sort
+findings=$(
+	if ! check_missing_docs
+	then
+		ret=1
+	fi
+
+	if ! check_extraneous_docs
+	then
+		ret=1
+	fi
+
+	exit $ret
+)
+ret=$?
+
+printf "%s" "$findings" | sort
+
+exit $ret