as for nginx backend for debug purpose I use python-tornado script, which will just give back params, which nginx pass to it.
so here it is:
upload under Chrome:
{u'upfile.path': ['/usr/local/apps/Opus/temp/upload/6/0009495446'], u'upfile.size': ['51'], u'upfile.name': ['test%22try.txt'], u'note': [''], u'upfile.md5': ['5a089ad5ea93048b0d492d53626bf76b'], u'upfile.content_type': ['text/plain']}
upload under Firefox:
{u'note': [''], u'upfile': ['erthtyjt\nrthy\ntrh\nrt\nh\nrt\nh\nrt\nh\nrth\nr\nth\nr\nth\n\nt\n\n']}

Chrome does character encoding, but Firefox - just backspace double quote sign.