CheckLog: make body-max-width disregard indented lines

Only lines starting with a non-whitespace character should be checked
against the limit. It's a common style to quote things with indented
lines and we like to make those lines free of any restriction in order
to keep the quoted text authentic.

lib/Git/Hooks/CheckLog.pm

@@ -165,8 +165,7 @@ sub body_errors {
     return 0 unless defined $body && length $body;
 
     if (my $max_width = $git->get_config($CFG => 'body-max-width')) {
-        my $toobig = $max_width + 1;
-        if (my @biggies = ($body =~ /^(.{$toobig,})/gm)) {
+        if (my @biggies = grep {/^\S/} grep {length > $max_width} split(/\n/, $body)) {
             my $theseare = @biggies == 1 ? "this is" : "these are";
             $git->error($PKG,
                         "commit $id log body lines should be at most $max_width characters wide, but $theseare bigger",
@@ -388,6 +387,11 @@ This option specifies a limit to the width of the commit log message's
 body lines, in characters. It's 72 by default. If you set it to 0 the
 plugin imposes no limit on the body line's width.
 
+Only lines starting with a non-whitespace character are checked against the
+limit. It's a common style to quote things with indented lines and we like
+to make those lines free of any restriction in order to keep the quoted text
+authentic.
+
 =head2 githooks.checklog.match [!]REGEXP
 
 This option may be specified more than once. It defines a list of

t/02-check-log.t

@@ -4,7 +4,7 @@ use 5.010;
 use strict;
 use warnings;
 use lib 't';
-use Test::More tests => 23;
+use Test::More tests => 24;
 use Path::Tiny;
 
 BEGIN { require "test-functions.pl" };
@@ -152,6 +152,15 @@ Body first line.
 The previous line has 73 characters.
 EOF
 
+check_can_commit('allow body with large quoted line', <<'EOF');
+Title
+
+Body first line.
+
+    123456789012345678901234567890123456789012345678900123456789001234567890123
+The previous line has 77 characters.
+EOF
+
 $repo->command(config => 'githooks.checklog.body-max-width', 0);
 
 check_can_commit('allow large body', <<'EOF');