reqHistoricalData: tzone argument does not seem to work correctly about ibrokers HOT 2 OPEN

This may help finding the error. After I set the time zone to the correct time 
zone:

Browse[3]> Sys.setenv(TZ="Europe/Istanbul")
Browse[3]> Sys.time()
[1] "2014-08-08 03:01:04.078636 EEST"   # CORRECT TIME
Browse[3]> reqHistoricalData(tws, twsEquity("SPY"), barSize="5 mins", 
duration="600 S", tzone="UTC")
waiting for TWS reply on SPY .... done.
                    SPY.Open SPY.High SPY.Low SPY.Close SPY.Volume SPY.WAP SPY.hasGaps SPY.Count
2014-08-07 21:50:00   192.19   192.27  192.14    192.18       3898 192.208      
     0       751
2014-08-07 21:55:00   192.19   192.22  192.06    192.11       4079 192.150      
     0       741
2014-08-07 22:00:00   192.10   192.22  192.08    192.21       4242 192.148      
     0       738
Browse[3]> reqHistoricalData(tws, twsEquity("SPY"), barSize="5 mins", 
duration="600 S", tzone="America/Chicago")
waiting for TWS reply on SPY .... done.
                    SPY.Open SPY.High SPY.Low SPY.Close SPY.Volume SPY.WAP SPY.hasGaps SPY.Count
2014-08-07 16:55:00   192.19   192.22  192.06    192.11       4079 192.150      
     0       741
2014-08-07 17:00:00   192.10   192.22  192.08    192.19       4253 192.148      
     0       741
2014-08-07 17:05:00   192.22   192.22  192.16    192.17        369 192.189      
     0        63

This is not the correct time for Chicago:
Browse[3]> Sys.setenv(TZ="America/Chicago")
Browse[3]> Sys.time()
[1] "2014-08-07 19:08:35.706916 CDT"

So, the ONLY way to get the correct results is to set TZ to GMT, which doesn't 
make any sense :(

Yes, I've verified that the function works correctly iff TZ="GMT"