new file mode 100644
--- /dev/null
+++ b/proxy_extra_data.t
@@ -0,0 +1,211 @@
+#!/usr/bin/perl
+
+# (C) Maxim Dounin
+# (C) Nginx, Inc.
+
+# Tests for http backend with extra data.
+
+###############################################################################
+
+use warnings;
+use strict;
+
+use Test::More;
+
+BEGIN { use FindBin; chdir($FindBin::Bin); }
+
+use lib 'lib';
+use Test::Nginx;
+
+###############################################################################
+
+select STDERR; $| = 1;
+select STDOUT; $| = 1;
+
+my $t = Test::Nginx->new()
+	->has(qw/http proxy cache rewrite addition/)->plan(20)
+	->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    proxy_cache_path cache keys_zone=one:1m;
+    proxy_cache_key $request_uri;
+    proxy_cache_valid any 1m;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location / {
+            proxy_pass http://127.0.0.1:8081;
+            add_after_body /after;
+        }
+
+        location /unbuf/ {
+            proxy_pass http://127.0.0.1:8081;
+            proxy_buffering off;
+            add_after_body /after;
+        }
+
+        location /head/ {
+            proxy_pass http://127.0.0.1:8081;
+            proxy_cache one;
+            add_after_body /after;
+        }
+
+        location /after {
+            return 200 ":after\n";
+        }
+    }
+}
+
+EOF
+
+$t->run_daemon(\&http_daemon);
+$t->run()->waitforsocket('127.0.0.1:' . port(8081));
+
+###############################################################################
+
+TODO: {
+local $TODO = 'not yet' unless $t->has_version('1.19.1');
+
+like(http_get('/'), qr/SEE-THIS(?!-BUT-NOT-THIS)/, 'response with extra data');
+
+}
+
+like(http_get('/short'), qr/SEE-THIS(?!.*:after)/s, 'too short response');
+like(http_get('/empty'), qr/200 OK(?!.*:after)/s, 'empty too short response');
+
+like(http_head('/'), qr/200 OK(?!.*SEE-THIS)/s, 'no data in HEAD');
+like(http_head('/short'), qr/200 OK(?!.*SEE-THIS)/s, 'too short to HEAD');
+like(http_head('/empty'), qr/200 OK/, 'empty response to HEAD');
+
+# unbuffered responses
+
+TODO: {
+local $TODO = 'not yet' unless $t->has_version('1.19.1');
+
+like(http_get('/unbuf/'), qr/SEE-THIS(?!-BUT-NOT-THIS)/,
+	'unbuffered with extra data');
+
+}
+
+like(http_get('/unbuf/short'), qr/SEE-THIS(?!.*:after)/s,
+	'unbuffered too short response');
+like(http_get('/unbuf/empty'), qr/200 OK(?!.*:after)/s,
+	'unbuffered empty too short response');
+
+like(http_head('/unbuf/'), qr/200 OK(?!.*SEE-THIS)/s,
+	'unbuffered no data in HEAD');
+like(http_head('/unbuf/short'), qr/200 OK(?!.*SEE-THIS)/s,
+	'unbuffered too short response to HEAD');
+like(http_head('/unbuf/empty'), qr/200 OK/,
+	'unbuffered empty response to HEAD');
+
+# caching of responsses to HEAD requests
+
+like(http_head('/head/empty'), qr/200 OK(?!.*SEE-THIS)/s, 'head no body');
+like(http_head('/head/matching'), qr/200 OK(?!.*SEE-THIS)/s, 'head matching');
+like(http_head('/head/extra'), qr/200 OK(?!.*SEE-THIS)/s, 'head extra');
+like(http_head('/head/short'), qr/200 OK(?!.*SEE-THIS)/s, 'head too short');
+
+like(http_get('/head/empty'), qr/SEE-THIS/, 'head no body cached');
+like(http_get('/head/matching'), qr/SEE-THIS/, 'head matching cached');
+
+TODO: {
+local $TODO = 'not yet' unless $t->has_version('1.19.1');
+
+like(http_get('/head/extra'), qr/SEE-THIS(?!-BUT-NOT-THIS)/s,
+	'head extra cached');
+
+}
+
+like(http_get('/head/short'), qr/SEE-THIS(?!.*:after)/s,
+	'head too short cached');
+
+###############################################################################
+
+sub http_daemon {
+	my $server = IO::Socket::INET->new(
+		Proto => 'tcp',
+		LocalHost => '127.0.0.1:' . port(8081),
+		Listen => 5,
+		Reuse => 1
+	)
+		or die "Can't create listening socket: $!\n";
+
+	local $SIG{PIPE} = 'IGNORE';
+
+	my ($uri, $head);
+
+	while (my $c = $server->accept()) {
+		$c->autoflush(1);
+
+		my $headers = '';
+		my $uri = '';
+
+		while (<$c>) {
+			$headers .= $_;
+			last if (/^\x0d?\x0a?$/);
+		}
+
+		$uri = $1 if $headers =~ /^\S+\s+([^ ]+)\s+HTTP/i;
+		$uri =~ s!^/unbuf!!;
+
+		$head = ($headers =~ /^HEAD/);
+
+		if ($uri eq '/') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 8\n\n");
+			$c->print("SEE-THIS-BUT-NOT-THIS\n");
+
+		} elsif ($uri eq '/short') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 100\n\n");
+			$c->print("SEE-THIS-TOO-SHORT-RESPONSE\n");
+
+		} elsif ($uri eq '/empty') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 100\n\n");
+
+		} elsif ($uri eq '/head/empty') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 8\n\n");
+			$c->print("SEE-THIS") unless $head;
+
+		} elsif ($uri eq '/head/matching') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 8\n\n");
+			$c->print("SEE-THIS");
+
+		} elsif ($uri eq '/head/extra') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 8\n\n");
+			$c->print("SEE-THIS-BUT-NOT-THIS\n");
+
+		} elsif ($uri eq '/head/short') {
+			$c->print("HTTP/1.1 200 OK\n");
+			$c->print("Content-Type: text/html\n");
+			$c->print("Content-Length: 100\n\n");
+			$c->print("SEE-THIS\n");
+		}
+
+		close $c;
+	}
+}
+
+###############################################################################