protect username '0'

Changes

@@ -4,6 +4,8 @@ Revision history for URI
     - Add a GH workflow to test LWP::Curl (GH#116) (Olaf Alders)
     - Add documentation examples for the host() and ihost() methods (GH#28)
       (Sebastian Willing)
+    - Remove colon from username:password if there is no password (GH#31)
+      (David E. Wheeler, Joenio Marques da Costa, Julien Fiegehenn)
 
 5.17      2022-11-02 17:03:48Z
     - Updated RFC references in the pod documentation for URI::file (GH#117)

lib/URI/_userpass.pm

@@ -40,7 +40,7 @@ sub password
 	$user =~ s/:.*//;
 
 	if (!defined($new)) {
-	    $self->userinfo($user || undef);
+	    $self->userinfo(length $user ? $user : undef);
 	} else {
 	    $new = "" unless defined($new);
 	    $new =~ s/%/%25/g;

t/userpass.t

@@ -1,12 +1,18 @@
 use strict;
 use warnings;
 
-print "1..1\n";
+use Test::More;
 
 use URI;
 
-my $uri = URI->new("rsync://foo:bar\@example.com");
+my $uri = URI->new('rsync://foo:bar@example.com');
+like $uri->as_string, qr/foo:bar\@example\.com/, 'userinfo is included';
+
+$uri->password(undef);
+like $uri->as_string, qr/foo\@example\.com/, 'set password to undef';
+
+$uri = URI->new('rsync://0:bar@example.com');
 $uri->password(undef);
+like $uri->as_string, qr/0\@example\.com/, '... also for username "0"';
 
-print "not " if $uri->as_string =~ /foo:\@example.com/;
-print "ok 1\n";
+done_testing;