SSE stops working after updating rack version to 1.4.3

[Ivan Aleksandrovich <intale.a@gmail.com>]

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Hi there. I want to notice that after updating rack version from 1.4.1 to 
1.4.3 the simple implementation of SSE stoped working for me(see 
application example in the attachment).
Gem list when that example works:

bundler (1.2.2)
daemons (1.1.8)
eventmachine (0.12.10)
haml (3.1.7)
rack (1.4.1)
rack-protection (1.2.0)
rake (10.0.2)
rubygems-bundler (1.1.0)
rvm (1.11.3.5)
sinatra (1.3.3)
thin (1.5.0)
tilt (1.3.3)

Gem list when that example doesn't work:
bundler (1.2.2)
daemons (1.1.8)
eventmachine (0.12.10)
haml (3.1.7)
rack (1.4.3)
rack-protection (1.2.0)
rake (10.0.2)
rubygems-bundler (1.1.0)
rvm (1.11.3.5)
sinatra (1.3.3)
thin (1.5.0)
tilt (1.3.3)

My environment:
 - Ruby version is ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-linux]
 - Ubuntu 12.04 (precise) 64-bit, Linux 3.2.0-35-generic, GNOME 3.4.2
 - Firefox 18.0
What do I mean by SSE doesn't work? - It tries to reconnect forever(with 
delay of a few seconds which is default for EventSource implementation - 
see http://www.w3.org/TR/eventsource/#the-eventsource-interface for me 
info, reconnection time option). You may see these reconnection retries in 
server logs or by opening "Network" tab in firebug

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