[Bristol] No service_code on passthrough updates.

The endpoint does not like it being present.

perllib/Open311/Endpoint/Integration/UK/Bristol/Passthrough.pm

@@ -20,4 +20,11 @@ around BUILDARGS => sub {
     return $class->$orig(%args);
 };
 
+around post_service_request_update => sub {
+    my ($orig, $self, $args) = @_;
+    # Bristol's endpoint gets confused if it receives a service_code on an update
+    delete $args->{service_code};
+    return $self->$orig($args);
+};
+
 1;

t/open311/endpoint/bristol_passthrough.t

@@ -0,0 +1,52 @@
+use strict;
+use warnings;
+
+BEGIN { $ENV{TEST_MODE} = 1; }
+
+use Test::More;
+use Test::MockModule;
+use JSON::MaybeXS;
+use Path::Tiny;
+
+my $pt = Test::MockModule->new('Open311::Endpoint::Integration::UK::Bristol::Passthrough');
+$pt->mock(endpoint => sub { '' });
+
+my $expected_update_post = <<XML;
+<?xml version="1.0" encoding="utf-8"?>
+<service_request_updates>
+  <request_update>
+    <update_id>2002</update_id>
+  </request_update>
+</service_request_updates>
+XML
+
+my $ua = Test::MockModule->new('LWP::UserAgent');
+$ua->mock(post => sub {
+    my $args = $_[2];
+    is $args->{service_code}, undef;
+    return HTTP::Response->new(200, 'OK', [], $expected_update_post);
+});
+
+use_ok 'Open311::Endpoint::Integration::UK::Bristol::Passthrough';
+
+my $endpoint = Open311::Endpoint::Integration::UK::Bristol::Passthrough->new;
+
+subtest 'POST update' => sub {
+    my $res = $endpoint->run_test_request(
+        POST => '/servicerequestupdates.xml',
+        api_key => 'test',
+        service_code => 'SE01',
+        service_request_id => 1001,
+        update_id => 123,
+        # first_name => 'Bob',
+        # last_name => 'Mould',
+        description => 'Update here',
+        status => 'OPEN',
+        updated_datetime => '2016-09-01T15:00:00Z',
+        # media_url => 'http://example.org/',
+    );
+    ok $res->is_success, 'valid request' or diag $res->content;
+    is $res->content, $expected_update_post;
+};
+
+done_testing;