[PATCH] lei rediff: fix construction of git-diff options

[Kyle Meyer <kyle@kyleam.com>]

When generating git-diff options, lei-rediff extracts the single
character option from the lei option spec.  However, there's no check
that the regular expression actually matches, leading to an
unintentional git-diff option when there isn't a short option (e.g.,
--inter-hunk-context=1 maps to the invalid `git diff --color -w1').

Check for a match before trying to extract the single character
option.

Fixes: cf0c7ce3ce81b5c3 (lei rediff: regenerate diffs from stdin)
---
 lib/PublicInbox/LeiRediff.pm | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/LeiRediff.pm b/lib/PublicInbox/LeiRediff.pm
index 3c8ebe41..2e793df5 100644
--- a/lib/PublicInbox/LeiRediff.pm
+++ b/lib/PublicInbox/LeiRediff.pm
@@ -108,8 +108,9 @@ EOM
 	push @cmd, '--'.($opt->{color} && !$opt->{'no-color'} ? '' : 'no-').
 			'color';
 	for my $o (@PublicInbox::LEI::diff_opt) {
-		$o =~ s/\|([a-z0-9])\b//i; # remove single char short option
-		my $c = $1;
+		my $c = '';
+		# remove single char short option
+		$o =~ s/\|([a-z0-9])\b//i and $c = $1;
 		if ($o =~ s/=[is]@\z//) {
 			my $v = $opt->{$o} or next;
 			push @cmd, map { $c ? "-$c$_" : "--$o=$_" } @$v;

base-commit: 2f720902ed702b64d918165ba21a96dabbeeca26
-- 
2.31.1