Shows list api with provides doesn't works

Steps to reproduce:

1. Create show function:
function(doc, req){
provides('text', function()

{ send('foo, '); send('bar, '); return 'baz!'; }

)
}

2. Make GET request to next resource:
http://localhost:5984/test/_design/foo/_show/send?format=text

3. Response would be 'baz!', but 'foo, bar, baz!' expected.

4. However, show function:
function(doc, req){
start(

{'Content-Type': 'text/plain'}

)
send('foo, ');
send('bar, ');
return 'baz!';
}
will return correct result.

5. And show function:
function(doc, req){
provides('text', function()

{ send('foo, '); send('bar, '); send('baz!'); }

)
}
will raise an TypeError expection:
{
error: "render_error"
reason: "function raised error: (new TypeError("resp is undefined", "/usr/share/couchdb/server/main.js", 817)) stacktrace: applyContentType((void 0),"text/plain; charset=utf-8")@/usr/share/couchdb/server/main.js:817 runShow(function (doc, req) {provides("text", function ()

{send("foo, ");send("bar, ");send("baz!");});},[object Object],[object Array])@/usr/share/couchdb/server/main.js:903 (function (doc, req) {provides("text", function () {send("foo, ");send("bar, ");send("baz!");}

);},[object Object],[object Array])@/usr/share/couchdb/server/main.js:991 ("_design/foo",[object Array],[object Array])@/usr/share/couchdb/server/main.js:1432 ()@/usr/share/couchdb/server/main.js:1475 @/usr/share/couchdb/server/main.js:1486 "
}

Both problem functions [1] and [5] works well if they are defined as list functions.