Description:
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I have set Error_Reporting(0) both in the script & in the php.ini.
I have an PHPBB forum (3.0.6) with zlib compression turned on.

Most of the warnings are gone, but in some cases (when some data is sent via POST), I am still getting a Notice "<b>date(): It is not safe to rely on the system's timezone settings.", and it is printed BEFORE compressed page body, so that browser reports broken encoding. 

After disabling zlib compression browser started to show notice and page content. After setting date.timezone in php.ini Notice is gone.

Reproduce code:
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Install PHPBB 3.0.6: turn zlib compression = on, make sure to unset date.timezone in php.ini. Then try to reply to a private message.

Expected result:
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No notices on the screen, no "broken encoding"

Actual result:
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HTTP/1.1 200 OK
Server: nginx
Date: Tue, 22 Sep 2009 13:09:15 GMT
Content-Type: text/html; charset=UTF-8
Connection: close
Expires: 0
Last-Modified: Tue, 22 Sep 2009 13:09:15 GMT
Cache-Control: private, no-cache="set-cookie"
Pragma: no-cache
Content-Encoding: gzip
Vary: Accept-Encoding
Content-Length: 3181

<b>[phpBB Debug] PHP Notice</b>: in file <b>/includes/functions_messenger.php</b> on line <b>390</b>: <b>date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Europe/Moscow' for 'MSD/4.0/DST' instead</b><br />
.............n.8...
V.&I[[..\j[..4.)..L..Y.E@I....U....
.Cv_...%{.)..%i.S#.E...d....>....9.t,..w./.............3..o../H..O.....u._9...N..;....^[fSw..{.T:.V<...i.:tF..ar..Dy[.t.<yb.....s..."h2.............h8j6.1.. ........2.,.-.H.C...hv.]d2 AD3...n|.:v.;........[here goes the rest of the compressed page]