add test case by geoff, thank you

src/tests/gunzip.vtc

+varnishtest ""
+
+server s1 {
+	rxreq
+	txresp -gzipbody {<Before esi1>
+<esi:include src="/esi1.html"/>
+Between esi1 and esi2
+<esi:include src="/esi2.html"/>
+After esi2
+}
+} -start
+
+server s2 {
+	rxreq
+	expect req.url == "/esi1.html"
+	txresp -gzipbody {<Before esi1-1>
+<esi:include src="/esi1-1.html"/>
+Between esi1-1 and esi1-2
+<esi:include src="/esi1-2.html"/>
+After esi1-2
+}
+} -start
+
+server s3 {
+	rxreq
+	expect req.url == "/esi2.html"
+	txresp -gzipbody {<Before esi2-1>
+<esi:include src="/esi2-1.html"/>
+Between esi2-1 and esi2-2
+<esi:include src="/esi2-2.html"/>
+After esi2-2
+}
+} -start
+
+server s4 {
+	rxreq
+	expect req.url == "/esi1-1.html"
+	txresp -hdr "Cache-Control: max-age=0" -gzipbody {esi1-1
+}
+} -start
+
+server s5 {
+	rxreq
+	expect req.url == "/esi1-2.html"
+	txresp -hdr "Cache-Control: max-age=0" -gzipbody {esi1-2
+}
+} -start
+
+server s6 {
+	rxreq
+	expect req.url == "/esi2-1.html"
+	txresp -hdr "Cache-Control: max-age=0" -gzipbody {esi2-1
+}
+} -start
+
+server s7 {
+	rxreq
+	expect req.url == "/esi2-2.html"
+	txresp -hdr "Cache-Control: max-age=0" -gzipbody {esi2-2
+}
+} -start
+
+varnish v1 -vcl+backend {
+	import ${vmod_pesi};
+
+	sub vcl_backend_fetch {
+		if (bereq.url == "/") {
+			set bereq.backend = s1;
+		}
+		elsif (bereq.url == "/esi1.html") {
+			set bereq.backend = s2;
+		}
+		elsif (bereq.url == "/esi2.html") {
+			set bereq.backend = s3;
+		}
+		elsif (bereq.url == "/esi1-1.html") {
+			set bereq.backend = s4;
+		}
+		elsif (bereq.url == "/esi1-2.html") {
+			set bereq.backend = s5;
+		}
+		elsif (bereq.url == "/esi2-1.html") {
+			set bereq.backend = s6;
+		}
+		elsif (bereq.url == "/esi2-2.html") {
+			set bereq.backend = s7;
+		}
+	}
+
+	sub vcl_backend_response {
+		set beresp.do_esi = true;
+	}
+
+	sub vcl_deliver {
+		pesi.activate();
+	}
+} -start
+
+client c1 {
+	txreq -hdr "Accept-Encoding: gzip"
+	rxresp
+	expect resp.status == 200
+	gunzip
+#	expect resp.bodylen == XXX
+#	expect resp.body == {XXX}
+
+	# XXX Fehler auch mit diesem Test (ohne Accept-Encoding)
+	# in dem Fall schlägt gunzip im Rahmen von Delivery fehl
+	# txreq
+	# rxresp
+	# expect resp.status == 200
+#	expect resp.bodylen == XXX
+#	expect resp.body == {XXX}
+} -run